0.21 minor .rle and .mc fixes

Found a problem with .rle processing and fixed a minor .mc issue.

Rustylife uses u32 nodeid/arena entries with u64 coordinates. This improves the hashing speed. Performance is maximized when the size of these hashes are minimized. This release uses a smarter algorithm to reuse garbage collected nodeids asap. This can speed up animation of some patterns 20-25%.

game_of_life - is a Linux executable
game_of_life.exe - is for Windows and was tested using wine

Run an executable and connect via a browser to http://localhost:7654/ and have fun. You can use the Edit button, then Cntrl+C to copy a pattern, and Cntrl+V to paste it into rustylife, then press Paste put the pattern onto the board. Use Play to run - it goes for about 126 million generations. Speed and Step control how fast it runs. Left click centers the board - you can also drag using the left mouse button. The mouse wheel zooms as does moving up or down holding both mouse buttons.

#Life 1.05
#N p_126m

5b4o$9bo$9bo$10b2o6$o$o$o10b2obobo2bo$b2o14bobo$b3o8b3o3b2o$b2o8b4obo
2bo$11bobo4bo$17b3o$14bobo2bo$11b2ob3obo$12b3ob4o!