Fix a crash when starting Cura.

[krop]

If LIB_SUFFIX is used when invoking CMake, we have to let Cura know where the
plugins can be found.

Fixes #347

[thopiekar]

Good work. There are only two things I would improve.

1. Add a fallback for the case someone runs Cura (uranium incl.) from source. In that situation there won't be a LibDir.py.
   So a try on the import would be nice.

2. Use as a file extension .py.in instead of .cmake. To be correct it is not a CMake file, but a .py which needs to be generated (.in).

[krop]

Your #2. is a matter of taste (we use foo.cmake for KDE projects to indicate it's a file CMake has to parse), but ok.
edit
Working on your #1, then I'll prepare the next PR to make cura packager-friendly (ie: use CMake as it should be)

[thopiekar]

Num 2 is based on how CuraVersion.py ist generated in Cura. Debian packagers are also adding this suffix often.
Also adding .py as prefix of the suffix makes it easier to understand that Python syntax is expected inside this file.

Num 1 is also implemented around CuraVersion.py. Since these projects are written in Python, most people like to skip the building part. So when someone is developing, then he can set the different PYTHONPATHs (incl build arcus and the engine) and she/he can start testing her/his changes directly.

[krop]

new PR incoming.

[Ghostkeeper]

Did you get around to making a new PR? I see what the problem is but it's hard to debug without setting up a whole VM with an installation that disambiguates between lib32 and lib64...

[krop]

Yes, @LipuFei merged it already (#350)