tigefa4u projects Trac

Provide a `to_datetime` utility function which can be used to convert from timestamps in various form (int, long and float) to `datetime` objects which are now used internally by Trac to represent dates (since [milestone:0.11]).

The various `trac.util.datefmt` utilities are using the above function so that they're robust w.r.t. non-migrated plugins, but they already document the stricter requirement to accept only `datetime` objects or `None` (the current time), which will be enforced in [milestone:0.12].

I also added a few unit tests.

Fixes #4547, based on Dave Abrahams' original patch.

WebAdmin: same as r5752 but for the 0.10 plugin. Thanks to agraham for the initial fix! Closes #3168

WebAdmin: fix upload plugin. Thanks to Dave Abrahams for the patch!

Closes #3168.

TracBrowser should be more robust when the changeset information is not available (e.g. blocked by authz)

Keep original msgid's case in msgstr's. Corrections, minor aditions.

Add top-level Czech directories.

Remove leftover debug print.

Context constructor no longer accepts realm, id, version etc. resource
descriptors. This fixes the wart where `Context(env, req, 'wiki', 'WikiStart')`
would not return an instance of `WikiContext`, while `Context(env, req)('wiki',
'WikiStart')` would. It also ensures that every resource is "rooted".

Add first version for Chinese.

Fill in headers.