Support for IRC calculations

[RaphaelRobidas]

Description of the desired feature
Intrinsic reaction coordinate (IRC) calculations generate the reaction pathway starting from the transition state. These calculations can be performed with most QM packages (such as Gaussian and ORCA), but are not currently supported by ccinput. They would be pretty simple to support, since there is no special input or necessary option.

Example of the usage and the desired output

$ ccinput gaussian irc M062X -bs def2tzvp -f TS.xyz -n 8 --mem 32G
%chk=calc.chk
%nproc=8
%mem=32000MB
#p IRC(CalcFC) M062X/Def2TZVP

File created by ccinput

0 1
<xyz structure>

Relevant documentation or examples
Gaussian documentation: http://gaussian.com/irc/
ORCA documentation: see the manual in the download section of the forums (https://orcaforum.kofo.mpg.de/app.php/portal)