tigefa4u projects Trac

Some cleanups for the Attachment code, in particular, don't use the env.href anymore.

Simple fix for the `ImageMacro` code introduced in [milestone:0.9.5], which failed to handle the size specified with "%". Reported in #3108.

Fixes the `ImageMacro` bug w.r.t. specifying size with "%", plus added unit-tests for macros (only for `ImageMacro` so far). Closes #3108.

Before the end of a WikiFormatting, flush unfinished code blocks. Fixes #1924.

TracRevisionLog and wiki history pages can now been printed. Thanks to Tim Hatch for pointing this out and for the initial patch. Fixes #3134

SpamFilter: log rejects at the `WARN` level.

Improve the way external links are displayed. The icon now always appear on the same line as the link itself. Unit-tested adapted and, along the way, moved around a few InterTrac tests that were out of place.

fix some inconsistencies in `sorted` from 2.4 implementation:
* ''always'' return a list, not the `reversed` generator returned when
reverse-sorting without a key function
* sorting should be stable w.r.t. the `key` function. When keys were equal
it was falling back to sorting on the original value

Cleanup in email notification unit test suite:
* Fix an important issue which may have cause to use previous test results while validating email recipients
* Split notification unit tests into a set of classes for supporting SMTP basic features, and the actual ticket notification tests
* Add a non-regression test for #3101
* Fix up documentation strings

Quick follow-up for r3277, fixing the unit-tests for trac-admin.