Inverts the given channels of the base image.
Mode may contain the characters "r", "g", "b", "a".
Only the channels that are mentioned in the mode string will be inverted.

Fixes #4323.

Add an [opacity:<r> texture modifier. Makes the base image transparent according to the given ratio. r must be between 0 and 255. 0 means totally transparent. 255 means totally opaque. Useful for texture overlaying.

Since the creation of minetest, it had no window icon on X11.
Now we have one.

The misc/minetest-xorg-icon-128.png file is a rendering of the
misc/minetest.svg file with inkscape, created with something like:

inkscape -z -e misc/minetest-xorg-icon-128.png -w 128 -h 128 misc/minetest.svg

Move version information into the window caption.

On popular player request.

Fixes #4209.

Adds initial ingame gamepad support to minetest.

Full Formspec support is not implemented yet and
can be added by a later change.

* Move key types into own file
* Use Generalized input methods in game.cpp

Add documentation, move files to a proper place and avoid memory leaks.
Make it work with most kind of texts, and allow backgrounds too.

Colored chat working as expected for both freetype and non-freetype builds. @nerzhul improvements * Add unit tests * Fix coding style * move guiChatConsole.hpp to client/

We can remove the function in MtNativeActivity now
as it serves precisely that purpose: to tell irrlicht
that we handled the esc key.

TODO for later:
 * Perhaps try to find a more performant container than KeyList

Fix warnings added by commit 01ae43c4

Fixes #3952

Also, rework the colorizing code to be more efficient.

Changes:
  * Fix indentation.
  * Pass strings by const reference.
  * Merge Strfnd and WStrfnd into one class instead of copying them.
  * Remove trailing spaces.
  * Fix variable names.
  * Move to util.
  * Other miscellaneous style fixes.

Fix two bugs related to the reconnect feature
introduced by commit

3b50b276 "Optional reconnect functionality"

1. Set the password to the stored one

Before, we have done the reconnect attempt with a
cleared password, so using the feature would only
work if you had an empty password.
Thanks to @orwell96 for reporting the bug.

2. Reset the reconnect_requested flag after its use

the_game only writes to the reconect_requested flag
if it sets it to true. It never sets it to false.
If the flag is not reset after its use, all "reset"s
to the main menu will look like the server had
requested a reconnect.

* Sky: rename Box => m_box and inline getBoundingBox
* Uniformize aabbox3d<f32> to aabb3f

The pageflip mode requires a stereo quadbuffer, and a modern graphic
card. Patch tested with NVidia 3D Vision.

The mini-map is not drawn, but that's what is done for topbottom and
sidebyside modes as well.

Also most of the time the user would prefer the HUD to be off. That's
for the user to decide though, and toggle it manually.

Finally, the interocular distance (aka eye separation) is twice as much
as the "3d_paralax_strength" settings. I find this a strange design
decision. I didn't want to chance this though, since it's how the other
3d modes interpret this settings.

- Add "thr_" prefix to thread utility functions
- Compare threadid_ts in a portable manner, where possible

- Add warning log level
- Change debug_log_level setting to enumeration string
- Map Irrlicht log events to MT log events
- Encapsulate log_* functions and global variables into a class, Logger
- Unify dstream with standard logging mechanism
- Unify core.debug() with standard core.log() script API

  * Rename everything.
    * Strip J prefix.
    * Change UpperCamelCase functions to lowerCamelCase.
  * Remove global (!) semaphore count mutex on OSX.
  * Remove semaphore count getter (unused, unsafe, depended on internal
    API functions on Windows, and used a hack on OSX).
  * Add `Atomic<type>`.
  * Make `Thread` handle thread names.
  * Add support for C++11 multi-threading.
  * Combine pthread and win32 sources.
  * Remove `ThreadStarted` (unused, unneeded).
  * Move some includes from the headers to the sources.
  * Move all of `Event` into its header (allows inlining with no new includes).
  * Make `Event` use `Semaphore` (except on Windows).
  * Move some porting functions into `Thread`.
  * Integrate logging with `Thread`.
  * Add threading test.

Enable the server to request the client to reconnect.

This can be done with the now extended minetest.request_shutdown([reason], [reconnect]) setting.

Use wide_to_utf8 and utf8_to_wide instead of wide_to_narrow and narrow_to_wide at almost all places.
Only exceptions: test functions for narrow conversion, and chat, which is done in a separate commit.

Adds everything needed for SRP (and everything works too),
but still deactivated, as protocol v25 init packets aren't final yet.
Can be activated by changing the LATEST_PROTOCOL_VERSION header to 25
inside networkprotocol.h.