Add lenis feature

[drammock]

should address the non-feature-contrasting issues:

1	2
k	k͉
p	p͉
t	t͉
t̠ʃ	t̠ʃ͉
f	f͉
s	s͉
ʃ	ʃ͉
pʲ	p͉ʲ
tʲ	t͉ʲ
l	l͉
n	n͉
b	b͉
x	x͉
tɕ	t͉ɕ͉
t̠ʃ	t̠͉ʃ

[drammock]

@bambooforest this one is ready, the diff is a little hard to read but it adds a lenis column that exactly parallels the fortis column except for the two diacritics 0348 and 0349

[drammock]

This one now has a README update too, @bambooforest