Created `gpio_set_pullup` to configure pullups independently of direction.
Removed GPIO_INPUT_PULLUP direction type.
Added misc other helper functions in iomux.h
Seems I got the functionality of this bit inverted when
initially testing.
In testing it also seems open drain mode is ignored on some pins, which
still source current. Needs more investigation though (may be pullups
internal to the ESP modules or set by default in software.)
Relates to #45
- Fix dir-locals so emacs won't inject occasional tabs to case statements.
- Fix stray tab indentation in example programs. (Thx @pfalcon for pointing this out)
