(main) Cleanup empty lines, unused code and comments in pops model.
Update Containment module since RGen 3.6.1 supports more meta methods.

Support for eContainer, and eContainingFeature was added in 3.6.1.
The corresponding methods in the Containment Module are now not needed.
Add support for 'import' in egrammar.

This adds support for 'import' expressions in the egrammar parser. 
The support handles import as a special kind of function call (except
for the keyword 'import') it is indistinguishable from a non
parenthesized call and it is difficult to deal with as an expression
otherwise.

In this implementation, it is not the parsers responsibility to nest
parsing, it simply returns an ImportExpression model element.
Make Lexer initiate required modules.

Lexer logic expected certain modules to have been initiated already.
Make egrammar's parser support initiate Model constant.

Some usage patterns ended up not having Model constant defined.
Handle AST::Hostclass having nil parameters (instead of empty list).

This happened when dumping an AST produce by classic parser.
Make Parser::Files initialize expected containing modules.

New usage patterns requires this file before modules are
initialized.
Make Scope require 'puppet/parser' instead of 'puppet/parser/parser'.

The scope has no business with the parser implementation. It only
needs the module constants initiated.
Add support for lambda following a named function call.
Make scope setvar produce a value.

This is required to enable blocks etc. to produce the last evaluated
expression.
Remove warnings about re-initialized constants when running tests.
Make environment use ParserFactory.

This enables switching parser.
Fix dump of VarDef and missing lambda in Function call.

VarDef name needed transformation to string (it is an AST::Name, not a
string). Output of lambda (pblock) in function was smiply missing.
(main) Cleaup calls to debugger.
Add import support to transformation, fix transforms.

This adds support for importing by instantiating the transformer with
an "importer" (capable of performing an import while transforming).

Several transformations that ended up setting "empty code" where instead
nothing should have been passed now corrected.
Turn on rescue/rethrow in parser support.

This turns on rescue and raise of parse exception. (When developing the
grammar part it is beneficial to get the underlying exception with the
grammar logic location/errors). This hides those details.
Fix problems in grammar referencing non existant rule results.

Some parts of the grammar was (is still not) covered by tests. 
Function calls with optional lambdas referenced non existing results.
Add indirection to parser instantiation, add support for egrammar.

This adds a ParserFactory that enables addition of a user supplied
switch between classic grammar/evaluation and egrammar (hard coded right
now to select the egrammar/transformation to ast route).
Change type's require from parser/parser to just parser.

The type does not need the actual parser, only the namespace.
Make typeloader use the ParserFactory instead of (classic) Parser.

This makes the type loader go via the user configurable switch.