RFC: Add unit test for splitting of numbers in TermGenerator

Summary:
Numbers are not handled as numbers, but literal strings. This is useful
for e.g. serial numbers ("1234-5678-90"), but less so for "real" numbers.

Integral numeric Properties are not fed through the term generator, so
these are handled correctly.

TODO: Determine expected behaviour for searching, i.e. is it ok do return
a document containing "12" when searching for "-12" and vice versa.

Reviewers: Baloo, Frameworks, ngraham, astippich

Reviewed By: Baloo, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D17284