Fix bug wherein gitignore-parser did not correctly match .gitignore glob
patterns like git actually does. Switch to parse-gitignore library and
add regression tests.
#9
Add _templatesFilter default derived special variable support.
#4
Change internal .gitignore default filtering to use the resolved path name
(e.g., "foo/bar.txt") instead of unexpanded template path (e.g.,
"{{varForFoo}}/bar.txt").
