Add regexp_splitter for builtin word splitter

Make re2_splitter builtin function and create new splitter
which supported oniguruma library.
add new feature: online clustering with coreset
Write test for empty match and fix it
Append check code
Fix config
Insert static_cast to sepcify method to call
#495 Replaced strerror with strerror_r
Merge pull request #510 from unnonouno/fix-onig-split

Write test for empty match and fix it
Eliminate moved test
Add version and idl-version option
Merge pull request #494 from jubatus/feature/onig_splitter

Add regexp splitter replacement for re2_splitter: fixes #471
Merge pull request #513 from unnonouno/fix-save-for-clang

Insert static_cast to sepcify method to call
Fix file format
Add logging for caught signal
Merge pull request #515 from gintenlabo/output-signal-name-log

Output signal name which stopped server
Fix tyo
Make version generate script
Add template of version.ml
Add gitignore to ignore version.ml
fix invalid use of iterator in inverted_index_storage (fix #498)