Revert the changes of 13194 on the class CmdLineArguments.
These changes are unnecessary and introduce some bugs,
for example the command line "-spec sv-comp" did not work anymore.

The desired goal of this commit was to allow multiple specifications
separate by comma, which is unnecessary because it is already possible
to specify the -spec parameter several times.


git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@13231 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c