Fix vertical misalignment of :: after angle brackets

[crespinl]

First of all, I'm a complete beginner when it comes to fonts, so I hope I did nothing bad.

The issue was caused by a rule that prevented :: and ::: from ligating when adjacent to < or >. Because the colons were kept separate, the second colon was independantly shifted upwards to align with the following uppercase letter, while leaving the first colon on the baseline.

By removing the ignore sub rules for colons next to angle brackets, :: now properly forms a single colon_colon.liga unit.

This fixes #1684, #1329 and #1225

[hunterhogan]

Perhaps fixes #1346.

Potentially affects #1061 and/or #980.

Current-ish glyphs

These are the same glyphs as 6.902HH but scaled down to 1000 units per em (because I'm in over my head). Regular weight. 36 pt.

PR 1685 glyphs

These are the glyphs from the PR, also scaled down to 1000.

Images with a difference layer

Text in the images

I copied and pasted text from Issues and one commit to make the following. I saw that you had tagged one of the issues as case-sensitive, so I added the lower-case "function".

::<
ClassName<type>::Function
ClassName<type>::function
aligns : and </> (<:, :<, :>, >:) 
:>: and :<: the
a <:< b means a =:= b means 
As <: is defined, 
::< ::> <:: >::
ecs.fetch::<Point>

thank you

Dude, my escapades into font files have convinced me that I never want to design a font. So, thank you very, very much for gifting us the benefits of your knowledge and hard work.