Added HyLambdaListKeyword tokens to the lexer

The name "lambda list keyword" is a historical artifact from the CLHS
and not optimal (http://clhs.lisp.se/Body/26_glo_l.htm).

The name may change at some point.
[WIP] Added lambda list keyword parsing step

This allows us to translate lisp argument lists to Python ones.

(defun foo (x y &rest z &optional {foo 3} &aux kwargs))

translates roughly to:

def foo(x, y, *z, foo=3, **kwargs):
  pass
Merge branch 'develop' into feature/lambda-list-keyword
WIP - Adding Call support and FuncionDef

The test is still broken, there are print statements... this is an
ongoing WIP and will get squashed before submitted the PR.
Added ast pretty printer
Merge branch 'develop' into feature/lambda-list-keyword
WIP - Move _parse_lamba_list to the functiondef
Got &rest working, tests pass

Did a little house cleaning in lex states.py too and started removing
stupid print() statements.
Merge branch 'master' into feature/lambda-list-keyword

Conflicts:
	hy/compiler.py
	hy/lex/states.py
	hy/util.py
	tests/compilers/test_ast.py
	tests/lex/test_lex.py
WIP - Added &key support
Added line and column offsets
Implemented &key and added tests
Removed redundant expression from _parse_lambda_list
Clean up based on review
Removed .format from lex/states.py
Allow variable without value in `let' declaration

Fixes issue #138

Signed-off-by: Julien Danjou <julien@danjou.info>
Allow fn to have no body

Signed-off-by: Julien Danjou <julien@danjou.info>
Remove the import-as and import-from builtins

The new and improved (import) can handle all cases import-as and
import-from did, so drop the latter two from the language. To do this,
the import builtin had to be changed a little: if there's a single
import statement to return, return it as-is, otherwise return a list of
imports.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
importer: doc update, MetaImport refactor

Signed-off-by: Julien Danjou <julien@danjou.info>
importer: remove useless import

Signed-off-by: Julien Danjou <julien@danjou.info>