Setfocus now works on macos dialogs by setting DLGSHIM_USE_SETFOCUS.
This option is only enabled __WXMAC__ is defined.
FixOSXCancelButtonIssue() is now called inside DIALOG_SHIM::SHOW.
All other calls from within the dialogs were removed.
* Refresh canvas when user cancels edits so that the discarded sheet is
cleared from the schematic.
* Add file name validation to the sheet properties dialog to prevent
illegal file name characters from being entered into the text control.
* Rename FOOTPRINT_NAME_VALIDATOR to FILE_NAME_CHAR_VALIDATOR for clarity.