Problems with common SMTLIB2 Strings for OpenSMT2 and Bitwuzla

[baierd]

Both OpenSMT2 and Bitwuzla need the removal of certain parts of SMTLIB2 Strings before we can parse them. Examples are comments and set-logic.
This is currently done lazily and incomplete. For example escape characters are not taken into account.
We should ask for better support by the developers and/or improve our filtering (possibly by using the branch for the SMTLIB2 parser).

[baierd]

Progress for OpenSMT2 + tests in branch improve opensmt2 parsing