Adds memory tracing in semi-flexible way. Vector implementations report copy
event to MemoryTracer, which forwards these to the registered listener.

The gnur Makefile has to be changed so that our gnur build also supports
memory tracing and we can use tracemem in tests.

Merge pull request #170 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/various_ffi to master

* commit 'b5160325':
  additions to native FFI

Merge pull request #164 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/special_dispatch to master

* commit 'f3fd86b7':
  implement "missing" using RDispatch.SPECIAL
  new RDispatch.SPECIAL for nodes that need direct access to their argument ASTs

* commit 'f43dc9dd':
  more consistent formatting in REngine.toString
  remove unnecessary error context overrides
  additional error info and loading from URL directly in Utils.getResourceAsSource
  additional profile in RCallNode
  additional profile in IsObject
  fix argument list of Sys.getenv
  fix gettext builtin (remove remnants from SUBSTITUTE implementation)

* commit '61acd432':
  various interop fixes and improvements

Merge pull request #174 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/internal_evaluatedargsvisitor to master

* commit '7f234761':
  let EvaluatedArgumentsVisitor consider .Internal builtins

Merge pull request #173 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/lapply_peeling to master

* commit '1b458eb8':
  peeling initial iteration in lapply

* commit '9e014d99':
  test

* commit 'f9cd9395':
  Correct use of Source.internal()
  check style  fix; RPerfStats option fix
  Instrumentation refactoring. Retire RNodeTimer, REntryCounts; replace with RFunctionProfiler Retire FunctionUID replace use with SourceSection Refactor all context-specific instrumentation state into InstrumentationState class
  Enable rowsum test
  remove old FastROption
  row sum_matrix:  use AbstractVectors
  Rprof: move state into RContext
  Add support for storing Profiler in Context; more RSource cleanup/functions
  RowsumFunctions: cast pipeline review fixes
  Move RInternalInternalSourceDescriptions into RSource
  compiler fixes
  Tighten up Rsource methods, use getURI instead of getPath, set .internal() on internal sources Implement line.profiling
  Implement Rprof (no lineProfiling, memProfiling, gcProfiling)
  remove old  comment
  Implement rowsums_matrix (needed by summaryRprof); enable tests
  Change "description" to "name" in FunctionDefinitionNode. Fixes regression on source'd functions where name was lost (description is already used in Node for some other meaning)
  Provide access to Polyglot engine instance from Context

Merge pull request #167 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:bugfix/IOException_warnings to master

* commit 'aa92a44d':
  fix warnings for non-thrown IOExceptions

Merge pull request #168 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/remove_NamedRNode to master

* commit 'd210c2ee':
  remove NamedRNode (use field in RLanguage instead)

Merge pull request #166 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/reduce_arguments_subclasses to master

* commit '1252cb44':
  reduce the number of Arguments subclasses

Retire RNodeTimer, REntryCounts; replace with RFunctionProfiler
Retire FunctionUID replace use with SourceSection
Refactor all context-specific instrumentation state into InstrumentationState class

Merge pull request #162 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:bugfix/refcounting-lists to master

* commit '55fc122f':
  Avoid copying of temporary data when assigning to a list

* commit 'c8319850':
  Wrap only IOException to RuntimeException. Leave other exceptions untouched.
  Adjusting the code to not expect IOException from PolyglotEngine.eval and co.

Merge pull request #146 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:bugfix/field_substitute to master

* commit '160a5a4f':
  fix various warnings
  fix calls with erroneous "string" targets
  do not treat String constants specially when creating calls
  handle replacements of field accesses