compatibility fix and bugfixes

Compatibility fix:
- fix underlying mechanics to work with secret religion mechanics that are now in the base game
- remove some things that are now handled by similar things in the base game

- can now use Spymaster to convert provinces to your secret religion
- can now suggest secret conversion to almost anyone, but must be in the same location as them
- Heads of Faith can no longer secretly convert

- updated for 1.9

- set compatibility to 1.8.* (no code changes needed)
- added icon to personal interactions

- set compatibility to 1.5.* (no code changes needed)

Major update:
- the underlying implementation of the secret has been changed to be easier to work with and more easily combine with Sanctioned False Conversion (this is a breaking change)
- changes include that characters can no longer be "potentially" false converts but have to choose to get the secret or not
- the AI may choose to falsely convert under some circumstances

- fix bug with exposing
- reduced dependency on base game effects