tigefa4u projects Trac

Follow-up to r3348, need to be able to call get_mimetype without a content argument.

The !WikiProcessors can be user configurable as well (follow-up to r3345)

Our pysqlite2 cursor wrapper returns None istead of [] from fetchall to indicate an empty result set. This is non-standard and makes no sense. This fixes #3193.

WorkFlow: Merged log:trunk@...:3345

Refactoring of the known MIME type associations.

This is now configurable, in the `[mimeviewer]` section:
* the `mime_map` list is used for declaring new MIME types
and enumerating associated keywords or file extensions
* additionally, one can set `enscript_modes` and `silvercity_modes`,
which are lists of MIME type, mode and quality ratio associations
for those renderers.

This can be used for:
* assigning extra keywords/file suffixes to an
already known MIME type (#1283)
* adding support to new languages (#2874)
* force usage of Enscript instead of SilverCity
(or vice-versa) by overriding the default quality ratio
* adding extra languages to customized SilverCity (#2198)

Example:
{{{
[mimeviewer]
mime_map = text/x-idl:ice,text/x-dylan:dylan:dyl
enscript_modes = text/x-python:python:5,text/x-dylan:dylan
silvercity_modes = text/x-java:Java:5
}}}

Added some unit test for `get_mimetype` before doing a bigger refactoring.

Make it possible to escape the bold/italic formatting using the usual "!" prefix, and simplify the code accordingly.

Move some of the trac.util functions in dedicated modules:
* trac/util/text.py for the unicode and text formatting utilities
* trac/util/datefmt.py for the date formatting and parsing utilities
* reorganized a bit the remaining functions in __init__.py
1. algorithmic functions
2. os/sys utilities
3. crypto utilities
* adapted all the `import` statements for the above changes
* fixed a few remaining !TracError import from `trac.util`
(should be from `trac.core`).

Follow-up to r3339, taking into account r3241... Thanks cmlenz for being vigilant :)

Various small clean-ups in the Wiki formatter:
* break paragraphs also for the `system_message` div elements
* when calling a macro, don't scan the list of macros twice
* !InterWikiMap can be used as a dict
* lots of small improvements to the documentation
* /me added as one of the author/maintainer for the wiki code