Merge branch 'master' into vba-automation
fix up some import lines
remove the custom press() implementation

This is now handled in vba_wrapper.
use vba.step() instead of step()
replace one more step() with vba.step()
set_memory_at -> vba.write_memory_at

The set_memory_at function was moved into vba_wrapper. There's no reason
for that one to be defined in pokemontools.
get_memory_at -> vba.read_memory_at
placeholder for get_memory_range

But really, the old calls to get_memory_range should just be replaced
with code that uses vba.memory[:] directly.
fix some memory manipulation to use vba_wrapper
pass vba into get_memory_range
pass vba and registers into call()
pass vba and registers into get_stack
move get_stack into vba.crystal
move call into vba.crystal
remove get_memory_range
switch vba.crystal to have instance methods
Merge branch 'master' into vba-automation
fix a vba.py test (test_PlaceString)
combine some vba tests
move tests into test_vba.py

They didn't belong in pokemontools/vba/vba.py in the first place.