Issue #130: Fixed support for indenting by tab
Allow indent a block of code by selecting a range of lines
and pressing 'tab'. The behavior implemented is the same as
the one in Sublime Text editor since I found it intuitive enough.
#define xm_question_width 22
#define xm_question_height 22
static char xm_question_bits[] = {
0xf0, 0x3f, 0x00, 0x58, 0x55, 0x00, 0xac, 0xaa, 0x00, 0xd6, 0x5f, 0x01,
0xea, 0xbf, 0x02, 0xf6, 0x7f, 0x01, 0xea, 0xba, 0x02, 0xf6, 0x7d, 0x05,
0xea, 0xba, 0x0a, 0x56, 0x7d, 0x15, 0xaa, 0xbe, 0x1e, 0x56, 0x5f, 0x01,
0xac, 0xaf, 0x02, 0x58, 0x57, 0x01, 0xb0, 0xaf, 0x00, 0x60, 0x55, 0x01,
0xa0, 0xaa, 0x00, 0x60, 0x17, 0x00, 0xa0, 0x2f, 0x00, 0x60, 0x17, 0x00,
0xb0, 0x2a, 0x00, 0x50, 0x55, 0x00};