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- Reintegrated the other-tags branch into my staging branch.  Local edits were required to integrate with the changes from the event-api branch.

Fixed bug in anchors with no content. This involved refactoring the 'implicit sequence' concept (where a map and a sequence start on the same indent, but we read the sequence as more indented since the '-' is visually an indent).

Converted indexing to std::size_t, and fixed the Node templated overloads to properly index any index type (determining what is an index type is a bit of a hack - it should be is_convertible<T, std::size_t> (I think), but I just explicitly wrote down a list)

Added CMake scripts for other platforms\nFixed some bugs that gcc complained about\nFixed CR/LF vs LF bug

Combined the myriad ScannerExceptions and ParserExceptions to a single ParserException class that has a message and a line/column position in the file where the error occurred.

Instead of deriving different tokens from a base Token class, we now use an enumerated TOKEN_TYPE to distinguish types. This is so we don't have to cast all the time when parsing the resulting token stream.
Also, removed start/end stream tokens.

Renamed the valid/possible tokens to a single variable status with enums valid, invalid, and unverified.

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There's a bug (and question): should we test simple keys' validity BEFORE stuff or AFTER stuff?

Also messed around with multiple character peeking on the input, and got something working.

We're now using exceptions for errors, and scanning/pushing tokens is exception-safe (using a set of "limbo tokens").