nep1: prefer self to this

[timotheecour]

settles Anybody using self or this for procedures operating on "class" style object types? - Nim forum

rationale

• self is better (more DRY) than repeating type name with underscore:

proc fun(someLongTypeName: SomeLongTypeName, a: int)

• self is more common than this for this purpose:
  in nim repo:
  rg '(this: '| wc -l
  56
  rg '(self: '| wc -l
  235
• self is more searchable than this because this is more common in english:

crude stats because some references might correspond to this as a param name, but still illustrative:

rg '\bthis\b' | wc -l
    3580
rg '\bself\b' | wc -l
     764

• 50-50 argument: self is common in python (but this is common in js)

future work

• see nep1: prefer self to this #16927 (comment)

[juancarlospaco]

Another PR to replace all remaining this with self.

We should also remove {.this: self.} to be consistent, been several years Deprecated already.

[timotheecour]

Another PR to replace all remaining this with self.
We should also remove {.this: self.} to be consistent, been several years Deprecated already.

ok to both but in another PR (note that renaming 1st param from this to self is a potential breaking change in case user writes foo(this = bar, ...), but this is unlikely in practice; anyways, this can be discussed in another PR)

[dom96]

I like this change :)