ToDo for tangerine:

- external templates (,,=file-name or ,,@file_name)
- ",,"-escaping (,,,?)
- error handling
* general blocks (e.g. 100.times).  This is difficult.
* multiple character encodings (iconv)
* pass self to the template code
  * simplify escapers
  * make code smaller, less obfuscated(?)
* fix escaping and blocks
* fix indentation of blocks
- Disabling output: ,,:(foo="yep")
- Output using <<
- Output formats:
  - XML: automatically escape chars
  - RFC822 support (for mails, arch logs etc.)
- indent rectangles:
  a                      a
    ,,|("1\n\2\n3")  =>    1
  b                        2
                           3
                         b
- #[] shortcut: ,,['foo'] => ,,(self['foo'])
- fix xtest_blog_example