Added highlights.scm and slight changes to the grammar.js file

[osman362]

Changes made to the grammar.js file

• With Tree-Sitter you can create tests for the highlighting queries created
• Tests are written as normal source code files that contain specially-formatted comments that make assertions about the surrounding syntax highlighting
• The specially-formatted comments are line comments like the one in the grammar file but the function have to be named 'comment' to work correctly
• Therefore the function name was changed to 'comment'

  Block Comment

• BLOCK_COMMENT was modified because the old version of the regex-code didn't work throughout different lines of code (only for one just like the line comment)
• The new regex code for it was copied directly from MTillers 'comment' function inside his grammar.js file

  Nodes

• Underscores hide nodes inside a syntax tree were deleted to make highlight queries inside the highlight.scm file easier to write
• Making parts of the syntax tree visible lead to adjusting the tests inside the test/corpus folder that were created to test the context-free grammar

Syntax Highlighting

• Created the highlights.scm file
• Added Queries to the file
• The highlights query uses captures to assign arbitrary highlight names to different nodes in the tree.
• Highlight names are assigned to each node

[CLAassistant]

All committers have signed the CLA.