Add support for symbol tree view

[nicorikken]

Bring support for the Symbols View extension. This inherits the tag parsing from the symbols view package, which leads the matching regexes into ctags from out of the ctags-config file.
Subsequently this would also bring GLM support to the Symbols Tree View package. This might however require some additional fixup.

Ideally multi-line regexes are supported, to provide more context for matches. In this regard the GLM syntax is somewhat unfortunate. Ideally I would like to provide some information on the type of object with the name or id. Likewise, it would make sense to add support for unnamed definitions. I created an issue at the symbols-view project regarding multi-line regex support: atom/symbols-view#189

I'm very eager to hear from daily GLM users about the that details should be visible in symbols view.

[nicorikken]

Regarding name, a regex like ^\s*name\s+(\w)* could perhaps be sufficient.