Dehinter

- changed min Python version to Python 3.6+ interpreters
- added support for default VDMX table removal
- added `--keep-vdmx` option to keep original VDMX table
- updated fontTools dependency to v4.0.0
- changed configuration to build wheels for Py3 only
- setup.py file updated with new classifiers
- added new Ubuntu-Regular.ttf testing file with the UFL license
- added the Roboto testing file license

- modified `glyf` table instruction set bytecode removal approach for composite glyphs
- fixed: `head` table flags bit 4 is now cleared only when `hdmx` and `LTSH` tables are removed (or were not present and bit is set in the font)

- add `--keep-cvt` option to keep original cvt table
- add `--keep-fpgm` option to keep original fpgm table
- add `--keep-gasp` option to keep original gasp table
- add `--keep-glyf` option to keep original glyf table
- add `--keep-hdmx` option to keep original hdmx table
- add `--keep-head` option to keep original head table
- add `--keep-ltsh` option to keep original LTSH table
- add `--keep-maxp` option to keep original maxp table
- add `--keep-prep` option to keep original prep table
- add `--keep-ttfa` option to keep original TTFA table

- initial beta release

- pre-release for PyPI naming