Fix for issue #114

This prevents the compiler from thinking that it has a reference to
any variable before it's actually output the assignment for said var.
More succinct random filter
Reverse order of context/frame lookup (issue #119)
Add urlencode filter
Merge pull request #118 from mattbasta/varfix

Fix for issue #114
Merge pull request #121 from mattbasta/betterandom

More succinct random filter
Merge pull request #122 from mattbasta/loopfix

Reverse order of context/frame lookup (issue #119)
Merge pull request #123 from matthewwithanm/urlencode-filter

Add urlencode filter