Misc. typos (#1384)

Found via `codespell`

docs/advanced/cast/eigen.rst

@@ -275,7 +275,7 @@ Vectors versus column/row matrices
 Eigen and numpy have fundamentally different notions of a vector.  In Eigen, a
 vector is simply a matrix with the number of columns or rows set to 1 at
 compile time (for a column vector or row vector, respectively).  Numpy, in
-contast, has comparable 2-dimensional 1xN and Nx1 arrays, but *also* has
+contrast, has comparable 2-dimensional 1xN and Nx1 arrays, but *also* has
 1-dimensional arrays of size N.
 
 When passing a 2-dimensional 1xN or Nx1 array to Eigen, the Eigen type must

docs/changelog.rst

@@ -597,7 +597,7 @@ Happy Christmas!
   being (notably dynamic attributes in custom types).
   `#527 <https://github.com/pybind/pybind11/pull/527>`_.
 
-* Significant work on the documentation -- in particular, the monolitic
+* Significant work on the documentation -- in particular, the monolithic
   ``advanced.rst`` file was restructured into a easier to read hierarchical
   organization. `#448 <https://github.com/pybind/pybind11/pull/448>`_.
 
@@ -665,8 +665,8 @@ Happy Christmas!
        <https://github.com/pybind/pybind11/pull/527>`_.
 
 
-    3. This version of pybind11 uses a redesigned mechnism for instantiating
-       trempoline classes that are used to override virtual methods from within
+    3. This version of pybind11 uses a redesigned mechanism for instantiating
+       trampoline classes that are used to override virtual methods from within
        Python. This led to the following user-visible syntax change: instead of
 
        .. code-block:: cpp

include/pybind11/cast.h

@@ -1204,7 +1204,7 @@ private:
 #else
         // PyPy seems to have multiple problems related to PyUnicode_UTF*: the UTF8 version
         // sometimes segfaults for unknown reasons, while the UTF16 and 32 versions require a
-        // non-const char * arguments, which is also a nuissance, so bypass the whole thing by just
+        // non-const char * arguments, which is also a nuisance, so bypass the whole thing by just
         // passing the encoding as a string value, which works properly:
         return PyUnicode_Decode(buffer, nbytes, UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr);
 #endif

tests/test_smart_ptr.cpp

@@ -19,7 +19,7 @@
 
 // ref<T> is a wrapper for 'Object' which uses intrusive reference counting
 // It is always possible to construct a ref<T> from an Object* pointer without
-// possible incosistencies, hence the 'true' argument at the end.
+// possible inconsistencies, hence the 'true' argument at the end.
 PYBIND11_DECLARE_HOLDER_TYPE(T, ref<T>, true);
 // Make pybind11 aware of the non-standard getter member function
 namespace pybind11 { namespace detail {