Changed handling of quoted strings in the menu parser for consistency

Changed handling of quoted strings in the menu parser for consistency

As reported by Amadeusz Sławiński, the support for (d)quoted string
in the menu file was not exactly the same as in previous versions
of WindowMaker, so we had a regression which is not acceptable.

This patch propose a consistent handling for (d)quoted text instead
of the previous on-the-title-only code; now all (d)quoted strings
are still kept as-is (as expected) but the (d)quotes are always
removed.
As a side note, it also improve the support for \escaped character
to work correctly as mentioned in the example of the default menu.

Note: This reverts b2e7620868aa18cebb8f6d1e653f8c46dc959a34 which
was an incomplete solution to the problem.