Create .add.extension(extenstion, reader) function for supporting external readers

This allows the addition of custom readers.
rename test (for compatibility with master)
Merge branch 'master' into extensions

Conflicts:
	DESCRIPTION

Resolved using recorded resolution.
export translate.dcf function
need to setwd back to delete test_project directory in test
Merge branch 'master' into extensions
Merge branch 'master' into v0.5-rc
typo
Merge branch 'master' into v0.5-rc
Merge branch 'extensions' into v0.5-rc
refer to PR
Merge branch 'v0.5-rc' into v0.5-rc-full