Molpro: add the ability to specify a custom parallel launcher

[valtandor]

This addition to the EasyBlock allows the user to specify, in the easyconfig, a launching string if a different MPI launcher is used (for example, srun).

[boegel]

path is the same in both if and else bodies, so hoist it above the if?

[valtandor]

In fact, in one case self.installdir was used, and in the other, self.full_prefix, so not the same. However, I have set a variable destroot and used that instead, so that only one call to os.path.join is needed, and can be done outside the if statement.

[boegel]

@valtandor some minor remarks, please ping me when they're tackled since Travis doesn't notify of updates

[valtandor]

@boegel I will do, but it will need to wait for about two or three weeks as I'm on leave as of today with very limited access to my usual machines.

[valtandor]

@boegel: This should have the required changes implemented.

[boegel]

@valtandor while testing this, I noticed that the syntax here is not correct, i.e.:

$ grep '^LAUNCHER' $EASYBUILD_PREFIX/software/Molpro/*/*/bin/molpro
LAUNCHER= /path/to/software/impi/5.0.2.044-iccifort-2015.1.133-GCC-4.9.2/bin64/mpiexec -machinefile %h -n %n %x

the space after the =, that's just not right in a bash script...

This issue was already there in the easyblock however, you didn't introduce it. But we should fix this while we're at it.

This additional change fixes that problem, please review/merge: valtandor#4

[boegel]

@valtandor ping?