[italic_angle] Doesn't actually check that post.italicAngle is as calculated

[simoncozens]

I'm not sure what this check is claiming to do; here's what the comments say:

fontbakery/Lib/fontbakery/checks/opentype_italic_angle.py

Lines 113 to 114 in c995480

	# Checking that italicAngle matches the calculated value
	# We allow a 0.1° tolerance

But it does not! It only checks that the sign of the italic angle in the post table matches the sign of the calculated value:

fontbakery/Lib/fontbakery/checks/opentype_italic_angle.py

Line 115 in c995480

if calculated_italic_angle < 0.1 and value > 0:

fontbakery/Lib/fontbakery/checks/opentype_italic_angle.py

Line 126 in c995480

if calculated_italic_angle > 0.1 and value < 0:

Maybe that's all the check should do, I don't know. At the same time, if we calculated the italic angle as 15° and the font declares it as 5°, that feels like something the user might want to know, especially since we went to all the trouble to work it out.