improve Windows launch scripts
patch by Ala' Alkhaldi and Josh McKenzie for CASSANDRA-7503
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Remove misguided stack allocation optimisations

patch by Benedict; reviewed by Aleksey for CASSANDRA-7515
Merge branch 'cassandra-2.1' into trunk
ninja change default back to heap_buffers
Merge branch 'cassandra-2.1' into trunk