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.
/* XPM */
static char *no_entry_xpm[] = {
/* width height ncolors chars_per_pixel */
"32 32 3 1",
/* colors */
"a c red",
"b c white",
"c c none",
/* pixels */
"cccccccccccaaaaaaaaacccccccccccc",
"cccccccccaaaaaaaaaaaaacccccccccc",
"cccccccaaaaaaaaaaaaaaaaacccccccc",
"ccccccaaaaaaaaaaaaaaaaaaaccccccc",
"cccccaaaaaaaaaaaaaaaaaaaaacccccc",
"ccccaaaaaaaaaaaaaaaaaaaaaaaccccc",
"cccaaaaaaaaaaaaaaaaaaaaaaaaacccc",
"ccaaaaaaaaaaaaaaaaaaaaaaaaaaaccc",
"ccaaaaaaaaaaaaaaaaaaaaaaaaaaaccc",
"caaaaaaaaaaaaaaaaaaaaaaaaaaaaacc",
"caaaaaaaaaaaaaaaaaaaaaaaaaaaaacc",
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaabbbbbbbbbbbbbbbbbbbbbbbaaaac",
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaac",
"caaaaaaaaaaaaaaaaaaaaaaaaaaaaacc",
"caaaaaaaaaaaaaaaaaaaaaaaaaaaaacc",
"ccaaaaaaaaaaaaaaaaaaaaaaaaaaaccc",
"ccaaaaaaaaaaaaaaaaaaaaaaaaaaaccc",
"cccaaaaaaaaaaaaaaaaaaaaaaaaacccc",
"ccccaaaaaaaaaaaaaaaaaaaaaaaccccc",
"cccccaaaaaaaaaaaaaaaaaaaaacccccc",
"ccccccaaaaaaaaaaaaaaaaaaaccccccc",
"cccccccaaaaaaaaaaaaaaaaacccccccc",
"cccccccccaaaaaaaaaaaaacccccccccc",
"cccccccccccaaaaaaaaacccccccccccc",
"cccccccccccccccccccccccccccccccc",
};