Restore full verse-range expansion in BackEnd::parse_verse_list()

[LAfricain]

A previous fix (in the tag-color-highlighting branch) switched this
function's iteration from a popError()-driven while(vs++) loop to
indexed access via vs.getElement(i), to stop one malformed fragment
in a multi-reference list from truncating everything after it.

That change had a side effect: the old vs++ iteration transparently
expanded hyphenated verse ranges (e.g. "Jer 3:6-11") into one entry
per verse, but getElement(i) returns each range as a single,
unexpanded entry whose getText() only reports the start verse.
Every caller of parse_verse_list() -- the verse-list popup, the
sidebar cross-reference list, and bookmark tag-color highlighting --
was silently dropping the rest of any such range.

Empirically, for a ListKey element that represents a range,
getUpperBound() (and getLowerBound(), which mirrors it here) return
the END of the range; for a plain single verse they are equal to the
element itself. Detect that difference and, when present, walk every
verse from the element (start) through the upper bound (end) via
increment(), adding each individually -- restoring the original
full-range expansion behavior for every caller of this function.