Cmd line and output compatibility with go version.

This pull request updates the command line options and the output file to mimic the Go version. Also you can have more than one render run in an program invocation

Here is an example:
<pre>
java -Xms4096m -Xmx8192m -XX:+AggressiveOpts javarays/Raycaster 0.05 5
Starting render#1 of size 0.05 MP (223x223) with 8 threads. Completed in 1708 ms
Starting render#2 of size 0.05 MP (223x223) with 8 threads. Completed in 1711 ms
Starting render#3 of size 0.05 MP (223x223) with 8 threads. Completed in 1740 ms
Starting render#4 of size 0.05 MP (223x223) with 8 threads. Completed in 1714 ms
Starting render#5 of size 0.05 MP (223x223) with 8 threads. Completed in 1714 ms
Average time for rendering: 1718 ms
</pre>