Use "slanted" equal instead of "slant" equal

[MDLC01]

Context

Most modifiers use the past tense. This is not the case of .slant in lt.eq.slant and gt.eq.slant.

Formal proposal

Rename two sym symbol variants according to the following table.

Character	Current name	New name
⩽ LESS-THAN OR SLANTED EQUAL TO	lt.eq.slant	lt.eq.slanted
⩾ GREATER-THAN OR SLANTED EQUAL TO	gt.eq.slant	lt.eq.slanted

Breaking changes

lt.eq.slant and gt.eq.slant would no longer be valid.

Related proposals

This proposal is incompatible with #42.

[Enivex]

Most modifiers use the past tense

This doesn't seem true to me. Otherwise a lot more would have the -ed ending.

I would like to go the other way whenever possible. I find slanted to be unnecessarily verbose.

[MDLC01]

Yeah "past tense" is probably wrong. But most modifiers that are not just shape names (.eq, .tilde, or .quest in eq.quest) use an "adjectival" form (not sure what the right term is), which for verbs would be past participle, according to sijo on Discord. For example, .curly in angle.l.curly, .small in plus.small, .heavy in checkmark.heavy, and the very common .big and .double, are adjectives, while .struck in interleave.struck and the very common .stroked and .filled are past participles.