GitLab

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

Refactored some common whitespace-parsing code in scanning both scalars.
Implemented the flow collection tokens.

Added stream input to the regular expressions, greatly simplifying the usage (in particular, we no longer have to specify the number of characters to be checked).

Wrote a simplified regular expression parser to make life easier (it only does single matches; i.e., no one-or-more matches, etc.).
Fixed some of the whitespace/line break matching.