In some cases the GL context creation might success without error, but
the created version is one that we don't want (e.g. software GDI
rasterizer on Windows). Previously the Context class constructor just
exited the application and it was impossible to react on that from the
application side (for example reducing some context feature
requirements).
Now there is Platform::Context::tryCreate(), which returns either
created instance or `nullptr` if the instance creation failed with some
error. That is now used in all Platform::*Application implementations.
The only places where they aren't absolute are:
- when header is included from corresponding source file
- when including headers which are not part of final installation (e.g.
test-specific configuration, headers from Implementation/)
Everything what was in src/ is now in src/Corrade, everything from
src/Plugins is now in src/MagnumPlugins, everything from external/ is in
src/MagnumExternal. Added new CMakeLists.txt file and updated the other
ones for the moves, no other change was made. If MAGNUM_BUILD_DEPRECATED
is set, everything compiles and installs like previously except for the
plugins, which are now in MagnumPlugins and not in Magnum/Plugins.
Somebody would just want to defer context creation after parsing
arguments or doing some validations without any particular setup, thus
having to write even the {} is annoying.
Added missing tryCreateContext() implementations. Error messages are
printed only by tryCreateContext(), createContext() is only a thin
wrapper which exits the application if tryCreateContext() fails and
doesn't print any additional information on the output.
Hopefully I didn't break anything :-)