#389 Charge range needs extending

[Gareth Owen]

We have several compounds in ChEBI with charges of -10, -11, and -12, but the charge range search only allows searching for charges between -8 and +8. This needs to be corrected, as there is no easy way of finding such compounds. Thus when doing a text search the brackets and the hyphen are ignored, so a search for "(-12)", which ought to work, simply finds all of the compounds with '12' somewhere in the name.