WIP: #31 post-autotools cleanup - step 1

Parent issue: #31

This MR covers Step 1:

• Get i18n working (Windows and Linux) also reported in neduard/dia#3
• Produce dia.res file from dia.rc and dia.ico using winddows.compile_resources I think this might also be linked to this
• Remove #define HAVE_CONFIG_H
• Fix app icon
• Update "About" copyright year and website
• neduard/dia#3: Get dia-remote working
• Handle dia.mime and dia.keys
• Update plugins/strees TODO note
• Sync all #ifdefs with meson.build
• Confirm config.h.win32 is not needed - doesn't seem to have anything important
• Does "/Dia/Objects/Demo, Custom Lines - Flow - Bezierline" need special treatment? - meson test objects has no reference to 'Demo, Custom Lines'.

Additional changes:

• 1d62d95b: Fix Windows release build crashing (segfault).
• 7594708d: Fix issue where config.h is not found for wmf plugin (and xslt).