config: Added "jinja" as additional template renderer option
setup.py: Added *.jinja files for i18n message extraction
config: Fixed {% trans %} tag usage for tg2

The Jinja2 environment is not properly configured for i18n by the tg2
framework, so we have to do that ourselves. We do that in the
"after_config" hook, after the Environment has been created and is part
of the app_globals.
templates: Added Jinja2 base templates
templates: Converted "About" page to Jinja2
templates: Converted flight details templates to Jinja2
lib/helpers: Added datetime module to helpers

That enables us to use h.datetime in the templates
config: Enabled do expression extension for Jinja2

Useful for building lists with <list>.append()
templates: Converted flight list templates to Jinja2
templates: Fixed whitespace removal for i18n statements
templates: Converted statistics pages to Jinja2
templates: Converted tracking info page to Jinja2
templates: Simplified i18n title messages including links
templates/flights: Fixed registration/competition id escaping
templates: Removed Genshi remains from details-table.jinja
templates: Added more strings to i18n
setup.py: Added encoding and extensions to Jinja2 i18n extraction config
templates/flights/nav: Added "All Flights" to i18n strings
templates/clubs: Converted clubs list to Jinja2
templates/clubs: Converted club details page to Jinja2