Sort of cleanup the global variable recognition:

[xsawyerx]

This fixes the following cases:

$_[0]
$_[ 0, 1 ]
$+{ "bar" }
@+{ "bar", "baz" }

Idents are hard, so trying to separate the Ident for variables and global variables.

• Rename Ident as ClassIdent
• Move GlobalVariable from NonLiteral to Variable
• GlobalVarExpr is now a variation of Var{Scalar,Array,Hash}
  • It lists Scalar, Array, and Hash sigils
  • Then all the available characters for global variables
  • This allows us to have all the different uses of these variables
  • $# is a unique case because it needs to be independent, to not collide with VarArrayTop
• DigitsExpr (used in VarName) is removed
  • It's covered as a global variable
• VarName is cleaned up and VarIdentExpr is used instead
• VarIdentExpr uses VarIdent
• VarIdent (similar to SubNameNonQLike) will not allow global variables
• ArrowMethodCall must use SubNameExpr