tools (common/template): new `fallback` settings: `fallback` can be used to change fallback behaviour. By default, fallback is done on `default` theme, this can be set to an other theme with a string, or to a list of fallback. The list can also be empty is no fallback is desired (notably usefull for "main" themes, on which other themes may fallback). This setting replaces `css_default_fallback`.

syntax: glob
*.pyc
*.pyv
*.swp
*.swo
tags
twistd.log
twistd.pid
bridge_constructor/generated
_trial_temp/
sat.egg-info
*.un~
dist
MANIFEST
build
ctags_links/
Session.vim