Used SwWrtShell::CanInsert() instead as it's the one doing the job. The
_CanInsert was just a wrapper to Beep() when the result was false. Yuk!

Historically the internal zlib symbols were prefixed by z_ to not mess up with any system zlib symbols.
Keep this good habit even with zlib-1.2.5.

This macro also messed up static analysis of slickedit.

LGPLv3+/MPL1.1

This is stage one of a number of changes to improve this dialog.

This fixes a missing icon bug for writer. Writer tried to load
cmd/sc_editheaderfooter.png but only cmd/sc_editheaderandfooter.png
existed. Calc is using cmd/sc_editheaderandfooter.png so I assumed
this is the right way.

This reverts commit d0a69c9a because
make dev-install's smoketest is failing on --enable-debug and
reportedly no --enable-debug

This fixes the build of 'basic' on Windows.