fix issue #144: let Windows support ALT+X keys.

Convert ALT+[@-_] inputs to 'ESC  <ascii>' sequence, as defined by C1 ANSI Control Sequence:
http://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_set
ALT+[a-z] (that is, ALT + SHIFT + [A-Z] ?) seems not specified, but linux & jline handle them same as ALT + [A-Z], so I also included these keys.