Use time.time() instead of time.clock().

time.clock() counts the amount of processor time used, not wall clock
time, on Unix systems, and it's wall clock time we want here.

Fixes bug #3.
Fix some bad whitespace.

Combining tabs and spaces is not a good idea.
Provide default area if a zone isn't explicitly mapped to a specific
area, making it less likely that a bad configuration leads to the
whole device failing to initialize.

Fixes bug #4.