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 ScrollLt_win_width 14
#define ScrollLt_win_height 14
static unsigned char ScrollLt_win_bits[] = {
0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x60, 0x00, 0x70, 0x00, 0xf8, 0x0f,
0xfc, 0x0f, 0xfc, 0x0f, 0xf8, 0x0f, 0x70, 0x00, 0x60, 0x00, 0x40, 0x00,
0x00, 0x00, 0x00, 0x00};