Make CMakeLists.txt ready to release

[YarikTH]

Current CMakeLists.txt is not ready to be used. Need some work to prepare it.
TODO:

• setup install settings
• support add_subdirectory usage (test if is the main project, disable tests and examples if not)
• make sure all variables and options have prefix UREACT_

make sure all variables and options have prefix UREACT_

To make sure about the name of the options:
cmake -LA . | awk '{if(f)print} /-- Cache values/{f=1}' | grep -v '^CMAKE_' | grep -v '^ProcessorCount_'

Sample output:

build_examples:BOOL=ON
build_tests:BOOL=y

Need to add such a check in the Makefile as part of the repository sanity check.

[YarikTH]

Install would be added with a separate issue

[YarikTH]

Install target is added