Some changes to cmake build system to simplify the flags treatment and the python installation

[andriish]

Dear @scarrazza,

apfel is an important software that is used in many places, particularly in SuperChic MCEG by @LucianHL. The SuperChic in a phase of intensive development now and the main dependency, apfel, is recompiled multiple times per day. Therefore, it makes a lot of sense to improve the compilation process of apfel with e.g. amendments to the cmake build system:

• reduce the dependence of apfel on the unreliable python setuptools inpywrap/CMakeLists.txt
• add some simple informative printouts to all the cmake files
• add some boolean switches for the compilation with LHAPDF and Python

Hopefully you will find the changes useful.

Best regards,

Andrii

[andriish]

Tag @vbertone

[vbertone]

Hello @andriish,

thank for using apfel and for proposing the improvements above. As far as they are backward compatible, I'm fine with them.

Best, Valerio

[scarrazza]

Thanks @andriish, LGTM.

[andriish]

Thank you!