first step to porting to Windows

Does nothing particular, except get few informations from the registeredwindow.
ctypes-utils.jsm needs to be ironed out (ABI used for .so version and lib type
for .dll), and we'll probably have problems when declaring callbacks
(ctypes.stdcall_abi on 32bits ?).
* a step forward: actually create the icon (Shell_NotifyIcon)
* cleaning

The icon gets created but GetLastError always returns
ERROR_INVALID_WINDOW_HANDLE, at least under win7.

We should be fine with callbacks' ABI as they are defined outside ctypes-utils.
fix NOTIFYICONDATAW, NOTIFYICONDATAW_Vx_SIZE definitions
* refactor testing code
* create hidden proxy window (corresponding to our unique tray icon)
destroy tray icon, hidden window and window class on shutdown
fix icon definition
* un-/register windows (begin) => refactoring
* filter icon events (begin)
* refactoring
* attempt to set our WndProc on Moz windows
* store window Id as a string

Calling CallWindowProc or ctypes.FuncType from a WNDPROC added to a Firefox
window crashes. See
https://bugzilla.mozilla.org/show_bug.cgi?id=598679
https://bugzilla.mozilla.org/show_bug.cgi?id=671266

The problem does not seem to occur on non-Firefox windows (for ex. a a hidden
window that we created).

We'll try to test Hooks instead of WndProcs.
failed attempt to use a hook (WH_CALLWNDPROC) instead of a window procedure.

This works well until we try to SendMessage from our proxy window to Firefox
windows. SendMessage crashes when sending to a Firefox window with our hook
registered, or to *any* window (tested on our proxy window and arbitrary
launched programs).
fix SendMessage'ing to any window

still crashes for FF windows with our hook registered
* actually use a WndProc on moz windows
* include winnt files to .xpi

WndProc crashes, mentioned in bugs 598679 and 671266, were recently fixed by
915613 (thx bholley!).
* adapt to Log4Moz -> Log renaming (FF 27+)
* fix typo (Cu.reportError)
show/hide mechanism in place: clicking on tray icon or closing a window.

NOTE: a WndProc on each mozilla window is not needed for this.
don't cache and update windows[wid].visible, windowsCount, visibleWindowsCount

Because the number of windows will generally be small, this is not worth the
effort.
cleaning
* fix (Chat) imports for Thunderbird
* fix Window.attachWndProc

NOTE: WndProc crashes fixed in TB27+
attempt to use gtk3
Revert "attempt to use gtk3"

This reverts commit 769105c59b94713674e09638fd5aaa0a27108883.
display new mail ico (first steps)
move linux-ish FiretrayChat.jsm to linux/.

We'll probably create a FiretrayChat.prototype when/if we support chat in
winnt.