Syntax highlighting improvement

[levjj]

• changed handling of templates to support infinite nesting of interpolated templates
• fixed comment bug (#68)
• added basic support for regular expressions (will match any regular expression as long as it doesn't include spaces or escaped forward slashes). might detect a division operation as regular expression (see #62) and does not check for redundant regex flags (e.g. /foo/gii)
• themes reuse style objects to improve performance
• single and double-quoted strings are always terminated at the end of the line (unless escaped)
• superfluous closing curly braces will be highlighted as error
• added test suite with 16 tests for various JavaScript syntax chunks

[rksm]

Awesome, you get a Lively star! ⭐️

Thanks!