fix getting parent from cache. closes gh-378
Promot groupBy filter from swig-extras. Closes gh-383
Extract file system based functions into template loaders
added test with include
export loaders
Move loader files, rename, add path resolving to memory loader
Don't use class-based loaders, update some documentation
Add page for template loader docs, fix typo
add basic filesystem tests
Docs
Fix base path lookups, add to memory loader
Merge branch 'feature/template-loaders' of github.com:paularmstrong/swig into feature/template-loaders

Conflicts:
	docs/docs/loaders.html
	lib/loaders/filesystem.js
	lib/loaders/index.js
	lib/loaders/memory.js
	lib/swig.js
	tests/loaders.test.js