Make Q::simplify more viable

[jnsiemer]

Description

The function simplify is capable of more than we thought. This PR makes sure that any developer is aware of the possibility to use it as a trade-off between precision and memory usage.

This PR implements...

• new constants for Q : Q::MAX62 (as this is the maximum number that we can instantiate as a constant and fmpz), INV_MAX62, INV_MAX32 as constants to use for a fair trade-off reg precision and memory-usage.
• explanations and an example of how to use simplify with these constants
• ensurance that the sign does not change using simplify

for Q.

Testing

• I added basic working examples (possibly in doc-comment)
• I included tests for all reasonable edge cases

Checklist:

• I have performed a self-review of my own code
  • The code provides good readability and maintainability s.t. it fulfills best practices like talking code, modularity, ...
    • The chosen implementation is not more complex than it has to be
  • My code should work as intended and no side effects occur (e.g. memory leaks)
  • The doc comments fit our style guide

[Marvin-Beckmann]

I like the changes, but two more suggestions:

• also add a constant for 16 and maybe even 8 bits
• add a test for the simplify that ensures that the denominator is actually at most having that specific number of bits when we have provided it.ideally also for large rationals and such