Add count instruction to the test harness to simulate count modifier compound keys (e.g., 11j), and add basic tests for the tree view. ok stsp@

Also, overwrite - and | unconditionally when capturing screen dumps, and unset TOG_COLORS and TOG_DIFF_ALGORITHM in regress setup. All tweaks suggested by naddy@ ok stsp@

As suggested by stsp, rather than busy wait in the view loop, use pthread conditions to wait for the blame thread to signal completion before drawing the screen. We can add more conditions for other views when needed, but by keeping the general WAIT_FOR_UI instruction and flag, this should make their use context-dependent so we won't need more test harness WAIT_* instructions. ok stsp@

Requested by James Cook

Problem reported by James Cook with reproduction scripts Regression test case by jamsek, as a simplified version of James' scripts fix tested + ok jamsek

ok stsp@