sdist and PyPi tarball is not clean.

[Louwrensth]

The PyPi package for 1.4.1, contains the spurious build products, this is the diff after running python setup.py clean in the PyPi tarball:

[vandell@hpc-login03 ToFu]$ git diff --no-index --stat tofu-1.4.1-orig/ tofu-1.4.1/
 /dev/null => tofu-1.4.1/__pycache__/_updateversion.cpython-36.pyc |    Bin 0 -> 1064 bytes
 tofu-1.4.1-orig/tofu/geom/_GG02.cpp => /dev/null                  | 104230 ----------------------------------------------------------------------------------------------------------------------------------
 /dev/null => tofu-1.4.1/tofu/geom/_GG03.html                      |  64010 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tofu-1.4.1-orig/tofu/geom/_basic_geom_tools.c => /dev/null        |  23457 ------------------------------
 tofu-1.4.1-orig/tofu/geom/_distance_tools.c => /dev/null          |  32225 ----------------------------------------
 tofu-1.4.1-orig/tofu/geom/_raytracing_tools.c => /dev/null        |  39715 --------------------------------------------------
 tofu-1.4.1-orig/tofu/geom/_sampling_tools.c => /dev/null          |  34027 -------------------------------------------
 tofu-1.4.1-orig/tofu/geom/_vignetting_tools.cpp => /dev/null      |  22916 -----------------------------
 8 files changed, 64010 insertions(+), 256570 deletions(-)

This causes problems when building ToFu with pip (as done by EasyBuild), because it will not rebuild these build products. You'll get errors like AttributeError: module 'tofu' has no attribute 'geom'

See:
#221
#201
https://jira.iter.org/browse/IMAS-2613
Louwrensth/easybuild-easyconfigs@9adda48#commitcomment-35701902

I'll create a fix for this.