Changed three major types to four major types  in nodes.py
Support included blocks override
don't evaluate trans arguments twice.
fix previous commit, which was kinda nonfunctional
Fix the Mako-like environment.
typo
Fixes issue #77 by adding explanation to docs

Points out that the Django empty is replaced by the
Flask else.
Add a note about the else statement.
There is no need to initialize Environment#bytecode_cache.
Improve whitespace docs to reflect reality.

See also:
https://groups.google.com/d/msg/pocoo-libs/6DylMqq1voI/GXTbZJ1Tr-sJ
Merge pull request #137 from PaulMcMillan/improve_whitespace_docs

Improve whitespace docs to reflect reality.
Prevent default filter from throwing UndefinedError when boolean flag is used with StrictUndefined.
lstrip spaces (but not newlines) from block tags
add lstrip_blocks environment setting, fix lexer
remove debug code
document `lstrip_blocks`
clarify lstrip_blocks option
hash lstrip_blocks in lexer cache
add tests for lstrip_blocks option
Don't match variable or comment blocks, Use {%+ to disable lstrip_blocks behavior manually