Can't comment/uncomment a hatpos portion of a line

[tyru]

ref #26

gc$ (comment)

~Currently hatpos keymappings are linewise. They should work also characterwise-ly.~ ~I think this should be controllable by global variable. Because some users don't like this behavior. (however it should be enabled by default)~

Add a new mapping gc$ and separate with gci.

| is cursor.

int foo |= 1;

to

int foo // = 1;

gcui (uncomment)

This won't be supported. Because it complicates uncomment behavior such as printf("// comment");.

In comment and while normal-mode:

int foo // = 1;

to

int foo = 1;