keyboard add ability to specify temporary custom layouts

rb core allows you to load custom keyboard layouts

this patch adds the ability to load a keyboard layout in a buffer
the custom layout is temporary and does not overwrite the current layout

use like so:

    unsigned short kbd[64];
    unsigned short *kbd_p = kbd;
    if (!kbd_create_layout("ABCD1234\n", kbd, sizeof(kbd)))
        kbd_p = NULL;

    rb->kbd_input(buf,sizeof(buf), kbd_p);

Change-Id: I7be2bd4a1b4797a147fa70228a9749dc56ac052a

apps/plugins/lib/SOURCES

@@ -69,6 +69,8 @@ bmp_smooth_scale.c
 pluginlib_albumart.c
 #endif
 
+kbd_helper.c
+
 #endif /* HAVE_LCD_BITMAP */
 
 #ifdef HAVE_TOUCHSCREEN