Use a lookup table for subject_find_special_char
Merge pull request #130 from JordanMilne/find_special_lookup

Use a lookup table for subject_find_special_char
Fix memory leak when rendering images as HTML
Merge pull request #132 from JordanMilne/fix_render_leak

Fix memory leak when rendering images as HTML
spec:  Fixed date, version.

Closes #133.
Merge upstream changes