Added rudimentary cmake support

[ohmree]

At the moment this doesn't support installation (e.g. to /usr/include/) but it should be usable as a git submodule.

The include path is <QSerializer> which I'm not sure about (since it might be mistaken for an official qt header) so if that's a problem I'll need to think of a workaround.

[smurfomen]

yeah, it's look like ok. But i think, you must be include QSerializer AND src/qserializer.h to add_library and SHARED instead of INTERFACE for correct automoc generating by cmake.

So, if use it like this, i see this way to include QSerializer to external CMake-based project

External CMake-based project CMakeLists.txt:

add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/QSerializer)
target_link_libraries(${PROJECT_NAME} QSerializer)

In this case you have opportunity include QSerializer file to your code like this:

#include <QSerialzier>

change add_library(...) and i will merge this PR to master brunch.
And next, i think we have need move QSerialzier include file to some "include" folder. Cause if include QSerializer project to CMake like this - it is will be include all files from QSerializer folder, incluing examples folder, LICENSE and other.

i suggest my CMakeLists.txt version:

cmake_minimum_required(VERSION 3.14)

project(QSerializer LANGUAGES CXX)

set(
        HEADER_FILES
        "QSerializer"
        "src/qserializer.h"
    )

add_library(${PROJECT_NAME} SHARED ${HEADER_FILES})

include_directories(${Qt${QT_VERSION_MAJOR}Core_INCLUDE_DIRS})

if (NOT Qt6_FOUND)
    find_package(Qt5 COMPONENTS Core REQUIRED Xml REQUIRED)
endif()

target_include_directories(${PROJECT_NAME} INTERFACE ${${PROJECT_NAME}_SOURCE_DIR})
target_link_libraries(${PROJECT_NAME} INTERFACE Qt::Core Qt::Xml)

and after that in external CMakeLists.txt:

add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/QSerializer)
target_link_libraries(${PROJECT_NAME} QSerializer)

it should be work correct