* doc/logo/gpg4win-logo-icon.ico: updated gpg4win icon
* doc/logo/gpg4win-nsis-header-install-150x57.bmp: updated
	installation header
* doc/logo/gpg4win-nsis-header-uninstall-150x57.bmp: updated
	deinstall header
* doc/logo/gpg4win-nsis-install.ico: updated installer icon
* doc/logo/gpg4win-nsis-uninstall.ico: updated uninstaller icon
* doc/logo/gpg4win-nsis-wizard-install-164x314.bmp: updated install
	wizard icon
* doc/logo/gpg4win-nsis-wizard-uninstall-164x314.bmp: updated uninstall
	wizard icon
* src/file-ext.ico: new icon for encrypted files
* src/inst-gpg4win.nsi: update
* src/slideshow/beta.png: remove old image
* src/slideshow/context_menu.png: remove old image
* src/slideshow/file-ext.png: remove old image
* src/slideshow/gpgol.png: remove old image
* src/slideshow/launch_kleo.png: remove old image
* src/slideshow/slide1-gpgol.png: new slide image
* src/slideshow/slide2-gpgex.png: new slide image
* src/slideshow/slide3-kleopatra.png: new slide image
* src/slideshow/slide4-summary.png: new slide image
* src/slideshow/slides.dat: point slides to correct images