Add functionality to search only tryptic matches

[SimonVandeVyver]

this PR adds functionality to the index to match only tryptic peptides.
After searching the matches in the suffix array, we check for each match if trypsin could cut the queried peptide from the corresponding protein.

[pverscha]

I have checked and gone through the code and to me it looks ok. I do need to verify it with a few more in-depth tests to be 100% sure, but @tibvdm you can also already take a look at the code in this PR.

[pverscha]

I have checked this PR in detail, ran a lot of data validation tests and all is ok!