fix spelling errors (#1985)

dlib/algs.h

@@ -977,7 +977,7 @@ namespace dlib
     /*!A wrap_function 
         
         This is a template that allows you to turn a global function into a 
-        function object.  The reason for this template's existance is so you can
+        function object.  The reason for this template's existence is so you can
         do stuff like this:
             
             template <typename T>

dlib/cmd_line_parser/cmd_line_parser_kernel_abstract.h

@@ -55,7 +55,7 @@ namespace dlib
                                      parameter to main() 
                 sword            ::= any suffix of a string from argv where argv is the 
                                      second parameter to main() 
-                bword            ::= This is an empty string which denotes the begining of a 
+                bword            ::= This is an empty string which denotes the beginning of a 
                                      <word>.
 
 

dlib/external/libpng/png.c

@@ -1895,7 +1895,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
     */
 
    /* Data checks (could be skipped).  These checks must be independent of the
-    * version number; however, the version number doesn't accomodate changes in
+    * version number; however, the version number doesn't accommodate changes in
     * the header fields (just the known tags and the interpretation of the
     * data.)
     */

dlib/external/libpng/png.h

@@ -1866,7 +1866,7 @@ PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
  *
  * The integer return from the callback function is interpreted thus:
  *
- * negative: An error occured, png_chunk_error will be called.
+ * negative: An error occurred, png_chunk_error will be called.
  *     zero: The chunk was not handled, the chunk will be saved. A critical
  *           chunk will cause an error at this point unless it is to be saved.
  * positive: The chunk was handled, libpng will ignore/discard it.
@@ -2804,7 +2804,7 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
  * The simplified API hides the details of both libpng and the PNG file format
  * itself.  It allows PNG files to be read into a very limited number of
  * in-memory bitmap formats or to be written from the same formats.  If these
- * formats do not accomodate your needs then you can, and should, use the more
+ * formats do not accommodate your needs then you can, and should, use the more
  * sophisticated APIs above - these support a wide variety of in-memory formats
  * and a wide variety of sophisticated transformations to those formats as well
  * as a wide variety of APIs to manipulate ancillary information.

dlib/external/libpng/pngrutil.c

@@ -96,7 +96,7 @@ png_get_int_32)(png_const_bytep buf)
 png_uint_16 (PNGAPI
 png_get_uint_16)(png_const_bytep buf)
 {
-   /* ANSI-C requires an int value to accomodate at least 16 bits so this
+   /* ANSI-C requires an int value to accommodate at least 16 bits so this
     * works and allows the compiler not to worry about possible narrowing
     * on 32 bit systems.  (Pre-ANSI systems did not make integers smaller
     * than 16 bits either.)
@@ -2799,7 +2799,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
                &png_ptr->unknown_chunk);
 
             /* ret is:
-             * negative: An error occured, png_chunk_error will be called.
+             * negative: An error occurred, png_chunk_error will be called.
              *     zero: The chunk was not handled, the chunk will be discarded
              *           unless png_set_keep_unknown_chunks has been used to set
              *           a 'keep' behavior for this particular chunk, in which

dlib/external/libpng/pngwutil.c

@@ -868,7 +868,7 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
    interlace_type=PNG_INTERLACE_NONE;
 #endif
 
-   /* Save the relevent information */
+   /* Save the relevant information */
    png_ptr->bit_depth = (png_byte)bit_depth;
    png_ptr->color_type = (png_byte)color_type;
    png_ptr->interlaced = (png_byte)interlace_type;

dlib/queue/queue_kernel_1.h

@@ -134,7 +134,7 @@ namespace dlib
                 requires
                     - start points to a node in a singly linked list 
                     - start->last points to the next node in the list 
-                    - there are at least length nodes in the list begining with start
+                    - there are at least length nodes in the list beginning with start
                 ensures
                     - length nodes have been deleted starting with the node pointed 
                       to by start

tools/htmlify/htmlify.cpp

@@ -260,7 +260,7 @@ int main(int argc, char** argv)
             {
                 if (file_map[out_file] != in_file)
                 {
-                    // there is a file name colision in the output folder. definitly a bad thing
+                    // there is a file name colision in the output folder. definitely a bad thing
                     cout << "Error: Two of the input files have the same name and would overwrite each\n";
                     cout << "other.  They are " << in_file << " and " << file_map[out_file] << ".\n" << endl;
                     return 1;
@@ -532,7 +532,7 @@ void add_files (
             {
                 if (file_map[out_file] != in_file)
                 {
-                    // there is a file name colision in the output folder. definitly a bad thing
+                    // there is a file name colision in the output folder. definitely a bad thing
                     ostringstream sout;
                     sout << "Error: Two of the input files have the same name and would overwrite each\n";
                     sout << "other.  They are " << in_file << " and " << file_map[out_file] << ".";