debug methods waste time and memory

[cberzan]

Possible starter task for @chrisgioia64.

Profiler shows that the Util.debug() calls in AbstractPartialWorld.setValue() waste a lot of memory. Example:

        Util.debug("Setting var: " + var + " to " + value + ", replacing "
                + oldValue);

When BLOG is run in non-verbose mode, Util.debug() is a noop. But the string concatenation above is still performed, and it wastes time and allocates a lot of small String objects which are then never used. (In my profiler run, this was one of the top object-allocation hot spots.)

Possible solutions:

http://stackoverflow.com/a/2466662/744071
http://stackoverflow.com/a/6023505/744071
http://stackoverflow.com/a/6016955/744071

[cberzan]

@lileicc fixed this in #122.