- update README to reflect correct performance numbers

- add tasks to README
 - repair bug in events.rs that prevented most events in VCD file from being parsed
 - add some initial code for timeline scrubbing

src/vcd/parse.rs

@@ -1,4 +1,4 @@
-use num::BigInt;
+use num::BigUint;
 use std::collections::HashMap;
 use std::fs::File;