README: Remove Keymapper trigger key note, add Vkeybd mouse button note.

As the keymapper is still WIP/unstable, this should be omitted from user
documentation. Added note on mouse button trigger for virtual keyboard
as this was not noted in any user documentation.
MAEMO: Add "small" virtual keyboard pack to port packaging.
WII: Add "small" virtual keyboard pack to port packaging.
N64: Add "small" virtual keyboard pack to port packaging.
LINUXMOTO: Add "small" virtual keyboard pack to port packaging.
DINGUX: Add "small" virtual keyboard pack to port packaging.
GPH: Add "small" virtual keyboard pack to CAANOO port packaging.
GPH: Add "small" virtual keyboard pack to GP2X port packaging.
GPH: Add "small" virtual keyboard pack to GP2XWIZ port packaging.
GPH: Add "small" virtual keyboard pack to CAANOO debug port packaging.
GPH: Add "small" virtual keyboard pack to GP2X debug port packaging.
GPH: Add "small" virtual keyboard pack to GP2XWIZ debug port packaging.
PS3: Add "small" virtual keyboard pack to port packaging.
DEVTOOLS: Add "small" vkeybd pack to create_project postbuild script.
SYMBIAN: Add "small" vkeybd pack to port packaging.
CONFIGURE: Enable virtual keyboard support for Win32 builds.