permit reconnection of a given picoirc context

permit reconnection of a given picoirc context

This adds a reconnect command to picoirc to get an existing context to
reconnect. This is useful for accidental disconnects from wifi lines or
proxy timeouts.

Rearranged the main read event handler to ensure we test for eof after
reading properly.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>