test for void lambda
Allow lambda with Void return

Fixes #108
test for type checking of yield statement with no value
yield without an expression has type Void

Fixes #133
test for parsing of trailing semicolon
lex now checks indentation after trailing semicolon

Fixes #144
Merge pull request #318 from etrepum/trailing-semicolon-144

lex now checks indentation after trailing semicolon
Merge pull request #316 from etrepum/yield-133

yield without an expression has type Void
Merge pull request #315 from etrepum/void-lambda-108

Allow lambda with Void return
fix list builtin to handle all py3 operators and methods
python 2.7 does not support clear or copy