Merge pull request #319 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:feature/updateformula to master

* commit 'cb814e73':
  updateform external implemented + tests

* commit '3ca5d6ef':
  Optimized sending environments through channels plus minor fixes to channels implementation.

* commit 'f3cd1289':
  "Dead" specializations detected by rbdiag
  rbdiag supports external builtins (no chimney-sweeping atm)

* commit 'f222f71e':
  Step towards replacing bzip2/xz compression with Java implementation

* commit 'c7f9ce54':
  Regenerated tests.
  Copy a shareable structure only if its attributes are modified before sending a message through the channel.
  Without a single method with test annotation source tests are not picked up for execution.
  Corrected name of internal FastR function.

Copy a shareable structure only if its attributes are modified before sending a message through the channel.

* commit '115405bc':
  Handle GNU R timeouts (e.g a crash) during unit test generation

* commit '5d94d5f0':
  checkstyle fix
  refactor context creation/initialization to match TruffleLanguage createContext/initializeContext

Merge pull request #308 in G/fastr from ~ADAM.WELC_ORACLE.COM/fastr:feature/rstudio_integration to master

* commit '7cbefa14':
  Used more appropriate API call to retrive a path from source section.
  Temporary fix for on-demand source section generation.
  Minor fix to functions returning contexts.

Merge pull request #307 in G/fastr from ~ADAM.WELC_ORACLE.COM/fastr:feature/various_updates to master

* commit 'f196abf3':
  Fixes to the parse builtin.

* commit '00136165':
  add comment
  fix regression in embedded mode polyglot init

* commit '3ecc7ef3':
  Fix new invalid fallback handlers.

* commit '39bcf889':
  Log functions pipelines modified to accept complex values
  Tests output updated
  Log and La builtins refactored
  matrix filters added

Merge pull request #301 in G/fastr from ~ADAM.WELC_ORACLE.COM/fastr:feature/rstudio_integration to master

* commit '68ae6160':
  Browser context is now simulated.
  Added support for comparing SEXP-s and contexts from native side.
  Added preliminary support for keeping context objects across native calls.
  Simulating browser context.
  Missing modifications for copying back Java objects on nested upcalls.
  Copying back Java object on nested upcalls.
  Fixed a call to tracing macro.
  Changed return type of a native interface API call so that we can preserve Java objects correctly on the native side.
  ffi: maintain stack of jmpbuf ptrs; run callEnter/callExit on Rembedded dowfalls
  FFI: implement R_Preserve/ReleaseObject and add test
  Another addition to the native API.
  While deparsing GNU R structures we need to expand attributes.

* commit '1adf1a33':
  suite.py: add licenses to repositories

* commit '8af49c1e':
  Error message fixed
  Rebased on master

* commit 'b00cecff':
  fix some missing files in FASTR_NATIVE_DEV dist; add FASTR_UNIT_TESTS dist