make_release: Turn on optimisation when building aven for Microsoft
Windows.
configure.ac,src/img.c: Only use _putenv_s() under MSVC - mingw
doesn't provide it.
src/aven.cc: Simplify handling of command line under __WXMSW__,
fixing error if run with no parameters.
src/printwx.cc: Fix crash on "File->Print" or "File->Export" under
Windows XP, reported by Brian Clipstone.
lib/en_US.po: Add missing translation.
NEWS: Update.
src/printwx.cc: Minor code refactor.
Update debian packaging ready for 1.2.9-1
src/img.c: Make 4 internal functions static.
src/img.c,src/useful.h: Fix some glibc fortify source warnings.
src/img.c: Tweak recursive calls in img_read_item_ancient() and
img_write_item_ancient() to directly call the same function.
src/img.c: Remove pointless "future expansion" comment from
img_read_item_ancient().
src/img.c: Pass pimg->buf_len rather than literal 257.
lib/,src/cavernlog.cc: If we fail to start the external editor,
throw up an error box.
src/img.c: Simplify reading of labels in 3d v1 and v2 files.
NEWS: Update.
lib/ca.po,lib/de.po: Mark altered message as fuzzy in languages I
failed to before.
NEWS,configure.ac: Update for 1.2.10.
src/mainfrm.cc,src/mainfrm.h: Fix wxWidgets assertion when double
clicking on an anonymous station.  Reported by Kevin Dixon.