Use VERSION file to manage DTK version. VERSION file defines package version. It also decides the initial value of cached variable DTK_VERSION which controls the project version in cmake build system. VERSION file is not synchronized to DTK6, as DTK6 has its own VERSION file. One can still pass version to DTK_VERSION when running cmake configure. This is helpful for developers.
Signed-off-by: Yixue Wang <wangyixue@deepin.org>
Distributions actually prefer CMAKE_BUILD_TYPE being `None` (the default value) so that their CFLAGS/LDFLAGS are used instead of the cmake presets. Let's do not overwrite it with "Release".
* remove redundant "dtkwidget" in include directory;
* improve cmake, modify some variable names, use file() to collect
source files for scalability;
* add full target_link_libraries support.
Log: add full target_link_libraries support
Influence: all projects who include headers directly by path