(release 30) add application icon

[vadi2]

Adds an application icon for Windows so it doesn't look like shit in the start menu.

Before:

After:

[vadi2]

This one is ready for a review-review in case you feel burnt from last night @SlySven.

[SlySven]

The Qmake QMAKE_TARGET_COMPANY and QMAKE_TARGET_DESCRIPTION variables were introduced somewhere between Qt 5.3.2 and 5.5.1 you will need to include a version check before you introduce them otherwise I'd expect Travis CI to barf on Linux/Qmake for both Clang and GCC cases.

Also, Windows builds are the most likely (IMHO) to use Cmake rather than Qmake and you need to do the equivalent thing for that build system...!

[vadi2]

Those are windows-specific variables though and the Windows Mudlet is using Qt 5.6 - it won't be an issue (it's why Travis CI passed).

I'm going to update the description because it turned out to be too long for what Windows practically expects in its menus.

Forgot about CMake, will apply a similar fix there. Thanks for the catch.

[vadi2]

I added what I think will do the trick, but the cmake on windows build is broken - or at least I can't get it to work. It is broken in all sorts of ways and the closest I got it to working was using the CMake GUI + MinGW Makefiles to produce the following:

The C compiler identification is GNU 4.8.1
The CXX compiler identification is GNU 4.8.1
Check for working C compiler: C:/mingw32/bin/gcc.exe
Check for working C compiler: C:/mingw32/bin/gcc.exe -- works
Detecting C compiler ABI info
Detecting C compiler ABI info - done
Check for working CXX compiler: C:/mingw32/bin/g++.exe
Check for working CXX compiler: C:/mingw32/bin/g++.exe -- works
Detecting CXX compiler ABI info
Detecting CXX compiler ABI info - done
CMake Error at C:/Program Files (x86)/CMake/share/cmake-3.0/Modules/FindPackageHandleStandardArgs.cmake:136 (message):
  Could NOT find ZIP (missing: ZIP_INCLUDE_DIR)
Call Stack (most recent call first):
  C:/Program Files (x86)/CMake/share/cmake-3.0/Modules/FindPackageHandleStandardArgs.cmake:343 (_FPHSA_FAILURE_MESSAGE)
  cmake/FindZIP.cmake:77 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  src/CMakeLists.txt:363 (FIND_PACKAGE)


Configuring incomplete, errors occurred!
See also "C:/Users/Vadim.FURORENT/Desktop/New folder/CMakeFiles/CMakeOutput.log".

Fixing the cmake build on Windows isn't in scope of this PR, but I've filed an issue so we don't forget about it.

cmake hasn't been used to make Windows builds by the way, see compilation instructions - it's all good old g++.