Unlink bin

Fixes this error:

The project was not built due to "Could not write file:
/Users/coryli/Code/eclipse/bcode2013-scaffold/bin/examplefuncsplayer.". Fix
the problem, then try refreshing this project and building it since it
may be inconsistent

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Replace deprecated JRE_LIB with JRE System Library

Fixes this warning:
Classpath variable 'JRE_LIB' in project 'bcode2013-scaffold' is
deprecated: Use the JRE System Library instead

Signed-off-by: Anders Kaseorg <andersk@mit.edu>