This commit brings many changes:
1. Remove cotire;
2. Remove PCH files (stdafx.xxx) and mentions;
3. Rearrange and clean includes:
3.1. Remove core includes path, use full header path core/xxx;
3.2. Move object_ptr to separate file base/object_ptr.h;
3.3. Add missing includes;
5. Add forward decls;
6. Get rid of some Qt private parts;
7. Fix ALL compilation errors after removing cotire on Windows, Linux, MacOS.
Closes#133.
Related to #96.
Currently the build without implicitly included precompiled header
is not supported anyway (because Qt MOC source files do not include
stdafx.h, they include plain headers).
So when we decide to support building without implicitly included
precompiled headers we'll have to fix all the headers anyway.
Some major platform-dependent file operations refactoring.
All methods like "open file", "open file with", "show in folder"
were moved to core/file_utilities module with platform-dependent
backends. All methods interacting with DesktopServices made async.