[guilib] rename GUI_MSG_(DE)SELECTED -> GUI_MSG_SET_SELECTED to make it obvious what it does
[guilib] adds GUI_MSG_IS_SELECTED message and use this instead of querying radiobuttons directly
[guilib] use GUI_MSG_ITEM_SELECTED for getting the selected value of a spinner rather than querying it directly
[guilib] adds GUI_MSG_SET_LABELS for setting labels on a spinner, and use it in preference to direct setting on the control
[cosmetic] drop unused macro
[guilib] adds GUI_MSG_SET|GET_FILENAME to get and set the filename from an image control instead of querying directly
[guilib] use various GUI_MSG_* routines to save querying specific control types
[guilib] use SET_CONTROL_LABEL2 and GUI_MSG_SET_TYPE for setting/fetching info from edit controls rather than direct access
[guilib] use GUI_MSG_ITEM_SELECT to set the progress on progressbars and sliders
[gui] convert a bunch of GUI_MSG_RESET|ADD|SELECT_LABEL to use SET_CONTROL_LABELS
[cleanup] convert a few g_windowManager.SendMessage()'s to OnMessage()
Merge pull request #4739 from jmarshallnz/control_access_cleanup

Control access cleanup
fixed: use the proper make instead of calling 'make' directly

fixes builds on freebsd
cmake buildsystem
add tests needed by new u16 string stuff
wrap cmyth properly
move some more install related stuff to install script
move all install code to platform install script
allow building without doxygen
fix building with yajl2