Feat/non blocking for loading game info

[pavanvo]

This PR solving issue with main thread blocking, on loading .xml file with saved game.
Also this code can be used somewhere else
fixes #233

[Rampoina]

Spaces vs tabs, this codebase uses mostly tabs, let's try to keep it consistent :)

[Rampoina]

you forgot to include memory

[Rampoina]

Tested, works fine on my system 👍 (after including memory)

[Rampoina]

This is done in other places of the code with https://github.com/MegaGlest/megaglest-source/blob/develop/source/shared_lib/include/platform/common/simple_threads.h#L71
Although honestly your way seems cleaner to me.

[andy5995]

I see this is passing the Linux CI, but the build fails for me on Manjaro, using g++ (GCC) 12.1.1 20220730

[ 45%] Building CXX object source/shared_lib/CMakeFiles/libmegaglest.dir/sources/lua/lua_script.cpp.o
In file included from /home/andy/src/megaglest-source/source/shared_lib/include/util/utf8.h:31,
                 from /home/andy/src/megaglest-source/source/shared_lib/sources/graphics/gl/text_renderer_gl.cpp:21:
/home/andy/src/megaglest-source/source/shared_lib/include/util/utf8/checked.h:268:34: warning: 'template<class _Category, class _Tp, class _Distance, class _Pointer, class _Reference> struct std::iterator' is deprecated [-Wdeprecated-declarations]
  268 |     class iterator : public std::iterator <std::bidirectional_iterator_tag, uint32_t> {
      |                                  ^~~~~~~~
In file included from /usr/include/c++/12.1.1/string:45,
                 from /home/andy/src/megaglest-source/source/shared_lib/include/graphics/text_renderer.h:15,
                 from /home/andy/src/megaglest-source/source/shared_lib/include/graphics/gl/text_renderer_gl.h:15,
                 from /home/andy/src/megaglest-source/source/shared_lib/sources/graphics/gl/text_renderer_gl.cpp:12:
/usr/include/c++/12.1.1/bits/stl_iterator_base_types.h:127:34: note: declared here
  127 |     struct _GLIBCXX17_DEPRECATED iterator
      |                                  ^~~~~~~~
In file included from /home/andy/src/megaglest-source/source/shared_lib/include/util/utf8.h:32:
/home/andy/src/megaglest-source/source/shared_lib/include/util/utf8/unchecked.h:179:40: warning: 'template<class _Category, class _Tp, class _Distance, class _Pointer, class _Reference> struct std::iterator' is deprecated [-Wdeprecated-declarations]
  179 |           class iterator : public std::iterator <std::bidirectional_iterator_tag, uint32_t> {
      |                                        ^~~~~~~~
/usr/include/c++/12.1.1/bits/stl_iterator_base_types.h:127:34: note: declared here
  127 |     struct _GLIBCXX17_DEPRECATED iterator
      |                                  ^~~~~~~~
[ 45%] Building CXX object source/shared_lib/CMakeFiles/libmegaglest.dir/sources/map/map_preview.cpp.o
In file included from /home/andy/src/megaglest-source/source/shared_lib/include/lua/lua_script.h:18,
                 from /home/andy/src/megaglest-source/source/shared_lib/sources/lua/lua_script.cpp:12:
/home/andy/src/megaglest-source/source/shared_lib/include/xml/xml_parser.h:156:10: error: 'shared_ptr' in namespace 'std' does not name a template type
  156 |     std::shared_ptr<CallBack<void>> loadAsync(const string &path, const std::map<string,string> &mapTagReplacementValues, bool noValidation=false,bool skipStackCheck=false,bool skipStackTrace=false);
      |          ^~~~~~~~~~
/home/andy/src/megaglest-source/source/shared_lib/include/xml/xml_parser.h:27:1: note: 'std::shared_ptr' is defined in header '<memory>'; did you forget to '#include <memory>'?
   26 | #include "callback.h"
  +++ |+#include <memory>
   27 | #include "data_types.h"
[ 46%] Building CXX object source/shared_lib/CMakeFiles/libmegaglest.dir/sources/platform/common/base_thread.cpp.o
make[2]: *** [source/shared_lib/CMakeFiles/libmegaglest.dir/build.make:706: source/shared_lib/CMakeFiles/libmegaglest.dir/sources/lua/lua_script.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
/home/andy/src/megaglest-source/source/shared_lib/sources/platform/common/base_thread.cpp: In destructor 'virtual Shared::PlatformCommon::BaseThread::~BaseThread()':
/home/andy/src/megaglest-source/source/shared_lib/sources/platform/common/base_thread.cpp:95:17: warning: 'throw' will always call 'terminate' [-Wterminate]
   95 |                 throw megaglest_runtime_error(szBuf);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/andy/src/megaglest-source/source/shared_lib/sources/platform/common/base_thread.cpp:95:17: note: in C++11 destructors default to 'noexcept'
make[1]: *** [CMakeFiles/Makefile2:227: source/shared_lib/CMakeFiles/libmegaglest.dir/all] Error 2
make: *** [Makefile:111: all] Error 2
ERROR: MAKE failed.

@Jammyjamjamman are you able to build this?

[Rampoina]

@andy5995 like I mentioned in the other comment, @pavanvo forgot to #include <memory> like the compiler tells you, probably not needed for earlier gcc versions