Work towards v1.1 release

[NiklasHohmann]

Some things that need to be done for the v1.1 release. Feel free to add to the list

• update citation.cff
• add reference sea level curves (constant, maybe Miller et al. ?) and document choices
• add reference sea level curves (ramp, platform, detached ramp & platform) and document choices
• clear out code (e.g. one of the CA routines that does not work)
• write documentation