Log Message:
libchewing: Update to 0.5.1

Changelog:
What's New in libchewing 0.5.1 (May 18, 2016)
---------------------------------------------------------
* Bug fixed:
  - Fix wrong CHEWING_DATADIR definition in CMake build #222.
  - Fix j, k selection when symbol in between #149 #221.

What's New in libchewing 0.5.0 (May 2, 2016)
---------------------------------------------------------
* New feature
  - Add Carpalx keyboard layout support #217.

* Dictionary
  - Update dictionary #151 #155 #188 #191 #201.
  - Add debug tool: dump_database.
  - Sort tsi.src #212.

* Misc
  - Tweak several comments.
  - Fix libchewing document.
  - Remove old/dead code.
  - Improve code readability and consistency.
  - Update automake syntax #114.
  - Add test cases #169 #177.
  - Update Python sample code.
  - Add debug tool dump_database.
  - Integrate coverity scan in https://scan.coverity.com/.

* Platform-specific
  - Update README for OS X.
  - Set WITH_INTERNAL_SQLITE3 to true by default in MS-Windows.
  - Fix Visual Studio compiling warnings/errors #168 #171 #189 #190 #213.
  - Add a cmake option BUILD_DLL to enable building *.dll with MS VC++ #185.
  - Make the python binding of libchewing support Windows dll files #186.
  - Don't use SIGSTOP in MS-Windows.

* Bug fixed
  - Check if ld supports --no-defined #144.
  - Fix unexpected candidate disorder for '1' #153
  - Replace bash-izm '==' operator with '=' for test(1) # 158.
  - Fix several Coverity errors #172 #173.
  - Fix ChewingKillChar which is disabling OpenSymbolChoice #160 #181.
  - ㄅ cannot overwrite ㄆ in HSU and ET26 #170 #183.

* Successful stories:
  - Rime Input Method Engine (RIME) takes partial dictionary from
    libchewing.
  - PIME (writing input methods for Windows easily with Python) supports
    Chewing IM by default.