Update grammar based on Monaco Language PR

[alefragnani]

While developing the PR to add Pascal support in Monaco Editor, I have noted some errors in the current grammar. Also, a few updates could be made to add new features recently added in VS Code.

News Features / Updates

• Add code folding for $REGION
• Add < > as AutoClosingPair and SurroundingPairs
• Add "hex" as a new identifier for numbers
• Add #number as a valid string pattern

Fixes

• Remove " (doublequotes) as AutoClosingPair and SurroundingPairs
• 0x is not a valid number pattern
• -- is not a valid line comment pattern (like previoulsy fixed in Atom)
• "..." (doublequotes) is not a valid string pattern