Tests: fixed docstring
properties: use proper Sphinx deprecations docs
pypo: use depr. decorator, add depr. reason

Add the reason for the deprecation and for keeping the function around.
Taken from the original commit message.
styleguide: documenting deprecation of features
Styleguide: Add import to deprecation example

If not people might forget about it.
PEP8: ignore Mozilla roundtrip files
PEP8: E112 expected an indented block
PEP8: E113 unexpected indentation
PEP8: E265 block comment should start with '# '
PEP8: exclude E265, reduce noise
po2prop: expand test

Expand the test to two units to try replicate issue in bug 115.
fn tests: po2prop using bug 115 example

Created a functional test for po2prop using the example from bug 115.
This was not an issue it seems but we now have a test for --personality.
po2dtd: improve test readability
po2prop: add missing accesskey test
po2prop: use the source language accesskey if translations is missing

Fixes bug 115 comment 6
Remove unnecessary comment in requirements
Adjust comment in requirements
Cleanup: We already require lxml >= 2.1.0

So these checks are unnecessary.
Bug 3194 - Faulty error message while initializing properties storage

Just improving error message when unable to find encoding for a string.
Fixes #3194.
Minor cleanup