Added support for template plugins.
Updated template compiler to use compilation units and statement objects.
Removed default behavior to evaluate all code in a template block right away (superseded by the Exec plugin).
Added Echo, Include, Flow and Exception template plugins.
Immensely improved template error handling, with error messages now pointing to the right lines in the template files.
Added template open_tag escape sequence support.
Fixed template else, elif blocks causing indentation errors.
Fixed template include plugin not identifying the proper template path
Fixed template include plugin not propagating the context.
Better template error reporting on invalid template file.
Better template error on include error.
Fixed issue where TemplateFile would return AttributeError if __enter__ was not explicitly called.
Added Template.compiled method.
Fixed issues with exception and block issues in template.
Updated test suites.
Cleanup make files.
Updated template test suites.
Merge branch 'feature/adv-template' into unstable