Adds a simple QSortFilterProxyModel on top of TimeZonesModel and
reimplements filterAcceptsRow using QStringMatcher (supposedly faster
according to qtdocs).
REVIEW: 123740
BUG: 346681
FIXED-IN: 5.3.1
Not all zones have '/' so the splitting may not result in list of two
entries. Use last() instead of at(1) to avoid possible out of bounds
assert.
BUG: 339411
Still has couple missing features:
* no time in the tooltip yet (needs larger refactor)
* no order selection
* no default timezone (but last used is always saved)
* couple minor issues
REVIEW: 120314
CCBUG: 337564
Martin Klapetek