external photon mode same as photon modes in input file

Description

making external photon mode file also available for time-dependent photon runs. external photon mode file now has the same capabilities as the inputflag

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.

marked the checklist item I have added tests for all the new features added in this request. as completed

marked the checklist item I have added tests for all the new features added in this request. as incomplete

marked the checklist item I have checked that my code follows the Octopus coding standards as completed

changed the description

assigned to @micael.oliveira

requested review from @nicolastd

ready to be merged

Looks good to me.

changed milestone to %12.0

@nicolastd Do want to have a look at this, or shall I merge it?

@micael.oliveira I don't want specifically to look at it. I quickly check it and this looks good to me.

No problem. I asked because @jflick indicated you as reviewer.

approved this merge request

merged

mentioned in commit 683301ca

Thanks @nicolastd and @micael.oliveira