Add ability to specify template dir as argument

[jmcgill298]

This allows specifying the template directory to the parse function directly instead of having to use an environment variable. In addition to looking in the custom template directory, this allows a failure to fallback to the default directory. This comes from @jacdavi in #945

[jmcgill298]

This is a replacement of #945 that is affected be history rewrite

[jmcgill298]

This replaces #945