Use precompiled headers in Visual Studio.

Reuse the Xcode header file, Poedit-Prefix.pch, and force its inclusion
so that all the source files don't have to be modified.
Fix case of buttons labels to be consistent

Windows should use Sentence case, not Title Case, unlike other
platforms. Make sure the casing is consistent on all buttons.
Use AutoWrappingText for AttentionBar's explanation

This allows longer explanatory texts. Also add some border between it
and the buttons to separate them visually a bit.
Update wx to fix OS X Retina toolbar buttons size
Use lambdas instead of std::bind for AttentionBar actions
Slight tweaks to AttentionBar close button spacing
AttentionBar: use green instead of yellow for questions
Add ability to have a checkbox in AttentionBar

This makes it possible to have UI element such as "Always do it like
this" alongside the action buttons.
Fix typo in default --add-comments values

There was a missing colon in --add-comments=TRANSLATORS:
Allow further customization of the suggestions bar
Don't show suggestions icon tooltip on OS X

The handling of tooltips is too flaky there, they keep appearing all
over the place.
Update wx to fix broken Fuzzy button on OS X
Show comment icon in the list for autocomments too

Don't show it only for translator-created comments, but also for notes
for translators ("automatic comments").
Better status strings

Easier to translate (can't use plural forms for multiple free
variables), less complicated.
Fix out of date prefs on OS X when reopened

Because the preferences window is kept in existence once created and
data aren't transfered to it anew, the settings could get out of date
when showing the Preferences for the second (and more) time, if
something in the app changed them in the meantime.

Work around this by reloading them every time the prefs window is
activated or its tab changed. This still isn't perfect and may miss some
changes, but should be good enough for most cases.