Allow abbreviation matching in quickopen

Old benchmarks before/after:

QuickOpenBench::benchProjectFileFilter_setFilter():"5000-bar":
Before: 4.6 msecs per iteration (total: 74, iterations: 16)
After: 5.4 msecs per iteration (total: 87, iterations: 16)

QuickOpenBench::benchProjectFileFilter_setFilter():"5000-1__":
Before: 2.9 msecs per iteration (total: 94, iterations: 32)
After: 7.3 msecs per iteration (total: 59, iterations: 8)

QuickOpenBench::benchProjectFileFilter_setFilter():"5000-f/b":
Before: 3.1 msecs per iteration (total: 51, iterations: 16)
After: 3.6 msecs per iteration (total: 58, iterations: 16)

REVIEW:115226