refactor fastr package in style of foreign functions

...com/oracle/truffle/r/library/fastr/FastRCallCounting.java

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

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

...ry/src/com/oracle/truffle/r/library/fastr/FastRDebug.java

...rc/com/oracle/truffle/r/library/fastr/FastRDumpTrees.java

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

...rc/com/oracle/truffle/r/library/fastr/FastRPkgSource.java

...y/src/com/oracle/truffle/r/library/fastr/FastRSource.java

...c/com/oracle/truffle/r/library/fastr/FastRStackTrace.java

...c/com/oracle/truffle/r/library/fastr/FastRSyntaxTree.java

...ary/src/com/oracle/truffle/r/library/fastr/FastRTree.java

...y/src/com/oracle/truffle/r/library/fastr/FastRTypeof.java

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

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

...cle/truffle/r/nodes/builtin/fastr/FastRFunctionEntry.java

.../oracle/truffle/r/nodes/builtin/fastr/FastRTreeStats.java