remove -Ofast compiler option
implement reloading and reparsing of font when filechooser button is
triggered, as well as add a checkbox for stripping left bearings of
glyphs.
implement stripping of left bearing on load/rendering of glyphs
add ui to toggle visualisation of left bearing
make advance be bounding box when stripping bearings
implement rewriting of glyph files

Does not reproduce originally <empty/> xml elements, probably OK enough.
It rewrites the coordinates according to stripped left bearing; as well
as writing new advance values.
remove unused kernagic_find_glyph
Add mean based recomputation of right bearings

This can cause significant overlap for some glyphs like W, unsure of how
well this first attempt will work on real world fonts.
Fix error sign error in recomputation of metrics.
s/gtk_file_chooser_set_current_folder/gtk_file_chooser_set_filename/
Add information about generated side bearings to README
replace libc memory allocation routines with glibs
some slight improvements to cairo rendering code
Separate pair-wise kerning computation out into it's own files, preparation
for making it easier to experiment with alternative approaches.
Clean up and reorder core pair-wise kerning code to do less computation.

We now first compute the distance between glyphs; before potentially
collecting more statistics.
Added comment about further optimization removed dead code
add KERNAGIC_DEBUG env var for visualizing internals
Add another heuristic to kerning computation
improve gray pixels
remove dead definitions in header