log: lower case Log and Logf

Signed-off-by: Fam Zheng <famz@redhat.com>
ui: Add dummy status line and separate panel

Signed-off-by: Fam Zheng <famz@redhat.com>
ui: Use channel of interface to communicate with UI loop

UICmd is the abstract interface with method "Do". There's a single
channel view.ch to receive commands from other goroutines.

Signed-off-by: Fam Zheng <famz@redhat.com>