API CHANGE: Adds new methods (several overloads)
   OString::number()
   OUString::number()
and marks all of the existing fromValue() methods as deprecated.

The purpose of this change is to clean up call sites
by hiding the necessary casts.

The casts are necessary because of overload resolution rules which are
somewhat vague about which methods to choose when using integer types.

See mailing list discussion here:
  http://nabble.documentfoundation.org/replacing-OUString-valueOf-static-cast-lt-sal-Int32-gt-td4027989.html
  Subject: "replacing OUString::valueOf(static_cast<sal_Int32>) ??"

Change-Id: Id3d150a6525eb0334e41e2ec6640bb06cd790b43
Reviewed-on: https://gerrit.libreoffice.org/1625Reviewed-by: Luboš Luňák <l.lunak@suse.cz>
Tested-by: Luboš Luňák <l.lunak@suse.cz>