Clip to avoid glitches when drawing some non-monospaced graphical chars

Some graphical chars are drawn bigger than expected (when font is
supposed to be monospaced, but is actually not), overlapping neighbors
and creating glitches when cleared.

Conflicts:
	src-terminal/com/jediterm/terminal/ui/TerminalPanel.java
Merge pull request #63 from Plonk42/clip_char

Clip to avoid glitches when drawing some non-monospaced graphical chars