implement string & (doc)comment snippet types
implement string & (doc)comment snippet types

comments/documentation comments are currently not implemented due to
libdparse removing them on parsing.

Instead of manually using the DLexer struct, nullifying future caching,
we will wait for the next libdparse version, implementing token trivia
which contains whitespace, tokens & strings.

Fix #104

Pure-D/workspace-d,WebFreak001/workspace-d