Allow underscore _ at end of identifiers

[zzz125]

same topic on forum
http://forum.nim-lang.org/t/525

i'd like to have underscores in variable names at least
and with the latest "implicit self" feature ({.this: self.}) it allows to write code similar to this:
https://github.com/urho3d/Urho3D/blob/master/Source/Urho3D/Scene/Node.cpp#L48

with simple "class variable" access via "classVariable_.something"

[Araq]

A separator has nothing to do at the end of an identifier.

[zzz125]

maybe.
but virtually every language has trailing underscores
other options to use with implicit self are "m_var" or "mVar" are uglier than "var_"

example:
m_classVar.method =1
mClassVar.method = 1
classVar_.method = 1

[Araq]

They are not uglier than something that I cannot even talk about: "var with underscore (not to be confused with the other var without underscore)".

[johnnovak]

Massive downvote from me... This would introduce an ugly special case to the way Nim name resolution works for questionable benefits. More weird special cases => more sources for subtle and hard to find bugs.