todo

源码,标准c++用力

Implement ESC [ Ps m codes where Ps is:
	21  Cancel bold
	24  Cancel underline
	25  Cancel blink
	27  Cancel inverse video


Track down the bug that sometimes displays the wrong background color


Check if ESC H is implemented, and if it is, implement ESC [ Ps g
where Ps is:
	0 [default] clear tab
	3 clear all tabs

Look into ESC [ ? 6 l not undoing ESC [ ? 6 h