Add parsing errors for decay descriptors

When running HLT2 lines for the upgrade with wrong decay descriptors, the code runs smoothly without any error but returns zero candidates. That makes it very hard to debug what's going on (in my case I spent two days on figuring out that I confused Bs_0 with B_s0...). For Run 1 we had a parser and descriptor checker. Can this be reactivated? I define it as bug, as it is quite an important check.

PS: not sure whether this is the perfect place, but as it affects MCDecayTreeTuple as well, it might.