Improve/color syntax improvements

[Mwexim]

This pull request aims to fix the mess I added in #82. The syntax was odd, the behaviour not flexible enough and overall the features were limited.

• Removed the literal parsing for hex colours. You'll need to write color from hex "ff0000" instead of &ff0000
• Rewrote the comment parsing mechanism and made sure you can now use color codes together with hashtags.
  • For example: color from hex "#ffff00" would've thrown an error previously, but now it doesn't because the hashtag is followed by a valid colour code. This seems very unnecessary now, but I am planning to add some tag syntax for colours in the future that could use this.
  • Other behaviour remains the same.
• Added support for the 'alpha' value in RGBA (transparency).
• Added support for 3-digit hex values (and 8-digit hex values as well).
• Changed the ExprColorFromRGB pattern to take in a list of integers. I feel this is a lot more intuitive than the other pattern.
• Made FileParser#parseFileLines static (why was this not the case?)
• Fixed some tests

I am planning to release a notable design update for 0.2, which will merge the parsing of multiline tokens and comments into one structure.