geosop -l coredumps

[strk]

I was hoping to get a list of supported operations, but got an abort instead:

[strk@c19:/usr/local/src/geos/geos/src/main/build(main)] bin/geosop -l
terminate called after throwing an instance of 'cxxopts::option_not_exists_exception'
  what():  Option ‘l’ does not exist
Aborted (core dumped)

[Sandro Santilli <strk@…>]

In 921f88d/git:

Make geosop be nice upon being called with unknown switch

Print an error and exit with failure, rather than aborting.
Closes #1125

[strk]

For the record: --help prints the list of supported ops