[Terminal] ignores paths starting with tilde

[diver]

hrev49500.

Typing ~/config in Terminal doesn't let it be linked when holding Alt key.

[bonefish]

Implemented the handling of "~" and "~/..." in hrev49504. Paths starting with "~user" aren't handled (yet), but since they aren't used all that often in Haiku, I didn't feel it worthwhile to put in the extra effort to support those as well.

[diver]

Thanks!