tigefa4u projects Trac

i18n: `Translations.load` return a `NullTranslations` instance when the catalogs are not available.

This later makes the `add` fail:
{{{
NullTranslations instance has no attribute 'add'
}}}
So better ''not'' consider the translations are active in this condition.

0.11-stable: backported r8194 (support alternate db backend for unit-tests)

0.12dev: merged [8189:8193/sandbox/rework-testing], alternate db backend for unit-tests and Makefile improvements.

rework-testing branch: move the environment from the Makefile to a Makefile.cfg.sample file.

Copy the latter into Makefile.cfg and adapt to your local environment.
In case the Makefile.cfg file is missing, the Makefile should work like before r8189.

Add a ''known issue'' warning for expected test failure with Subversion 1.6.1 on Windows.

rework-testing branch: make it possible to run the unit-tests using the alternative database backend specified by the TRAC_TEST_DB_URI environment variable.

Decent speed is achieved by "resetting" the database instead of dropping all the tables (MySQL) or the schema (PostgreSQL). This reset operation clears all the data (`DELETE FROM` and `ALTER SEQUENCE` for PostgreSQL, `TRUNCATE TABLE` for MySQL).

As the support for alternative database backend mostly moved to `trac.test` and the `EnvironmentStub`, the code in `trac.tests.functional.FunctionalTestEnvironment` has been significantly simplified.

rework-testing branch: re-use utilities from the DB api for abstracting SQL dialect differences.

This is a first step towards running unit-tests with alternative database backends.

rework-testing branch: Makefile improvements

Make it easy to specify on the command line:
- which python version to use (`make python=<version>`), where `<version>` is one of 23, 24, 25, 26 or any other key defined in the Makefile. If no version is specified, this defaults to the python program currently in the PATH, as before.
- which db backend to use (`make db=<backend>`), where `<backend>` is one of postgres or mysql. If no backend is explicitly specified, the database backend defaults to the SQLite :memory: kind.

The setup for Python and database backends is for now placed in the Makefile itself, but I'll move that in a second step in a Makefile.cfg file.

0.12dev: port r8179, r8185 and r8186 from 0.11-stable.

0.12dev: prevent r8177 from being merged back.