Enhance each optimization with further info

[StErMi]

Each gas optimization should have this information:

• further knowledge links to understand why that change improves gas usage
• forge snapshot to compare A/B testing. How much gas are we going to get? People will also be able to test with different config (solidity version, compile flags and so on)
• With which solidity version and compiler flags these gas optimizations are true? From which Solidity version you can drop these "workarounds"?

[PaulRBerg]

Seconded. The last point, in particular, is critical because depending upon the compiler flags (e.g. optimizer) there might no difference between the suggested optimizations.