Allowed characters in annotation names/id

[pascaltimshel]

Problem

Currently, the only allowed characters in SPECIFICITY_INPUT are hyphens (-) and single underscores (_)
(Most recent changes introduced in this commit: 9e36418)

Proposed solution:

SPECIFICITY_INPUT should also allow dots (.) and plus signs (+).

[pascaltimshel]

@pvtodorov : I've assigned you to this issue for your inputs since you seem to understand the problem well. I respect if you don't have time to fix it.