[Templates] PROPOSAL: Allow named args to eval filter.

[Paul Seamons]

The Alloy eval filter allows for named args to be
passed that represent configuration items for the string
being eval'ed.  The current eval filter could rather easily be updated
to include this feature.  It could also be left until the TT3 release.

The configuration items that should be supported are:

  SYNTAX          # proposed item
  CACHE_STR_REFS  # proposed item
  ANYCASE
  INTERPOLATE
  PRE_CHOMP
  POST_CHOMP
  V1DOLLAR
  DUMP            # proposed earlier

Template::Parser::CET does not support this behavior because it uses
the TT2 engine and the eval filter from TT to play its compiled templates.

Template::Alloy supports this behavior.

  # works in Template::Alloy
  [% foo = '<TMPL_VAR EXPR="1 + 2">' %]
  [% foo | eval(syntax => 'hte') %]

Paul Seamons