Implementation of multicore parallel lapply function using FastR's contexts and channels.

.../src/com/oracle/truffle/r/library/fastr/FastRContext.java

.../oracle/truffle/r/library/parallel/ParallelFunctions.java

com.oracle.truffle.r.native/library/fastr/src/R/fastr.R

...om/oracle/truffle/r/nodes/builtin/base/foreign/FastR.java

...ruffle/r/nodes/builtin/base/foreign/ForeignFunctions.java

...ruffle/r/nodes/builtin/parallel/R/forkcluster_overrides.R

...e/truffle/r/nodes/builtin/parallel/R/mclapply_overrides.R

....r.runtime/src/com/oracle/truffle/r/runtime/RChannel.java