Add hlb lexer

[hinshun]

Hi @alecthomas, just wanted to experiment with various syntax highlighting libraries for HLB, a language I'm writing using participle.

I noticed that chroma doesn't seem to like the non-capturing group:

{`(\b((?!(scratch|image)\b)[a-zA-Z_][a-zA-Z0-9]*\b))`, ByGroups(NameOther), nil},

The equivalent from pygments:

(u'(\\b((?!(scratch|image)\\b)[a-zA-Z_][a-zA-Z0-9]*\\b))', bygroups(Name.Variable)),

I also included a pygments2chroma.hlb that allowed me to containerize the workflow to convert my pygments lexer, happy to exclude it.

[alecthomas]

Thanks! Try using chroma --trace to debug which rules are matching.

[hinshun]

I looked at haxe's example of using non-capturing group and updated my lexer to work for both pygments and chroma.

[alecthomas]

Nice! Can you add a test please? Instructions are in the lexers directory.

[alecthomas]

Thanks!