improve expand_filename considerably
fix absolute paths maybe
fix
updated path expansion (koenpunt)
Can't seem to get his commit for some weird reason for proper attribution:
https://github.com/sprinkle-tool/sprinkle/commit/e7e038ed847a0bb2f5d79e7aa1752bd711f67ce4
fixup render path searching for be much saner
search either pwd or template_search_path
fixup docs and example