configure.ac: add missing sphinx error message for OSX with Homebrew system
mrb: define Groonga::Object#== as equivalency check predicate
Add grn_expr_take_obj() as an internal experimental function
Export a function that allocates constant object in an expression internally

It is for mruby.
expr: suppress unused variable 'e' warning

`grn_expr *e = (grn_expr *)expr` is defined in `grn_expr_alloc_const()` internal.
Merge pull request #197 from cosmo0920/suppress-warning-expr

expr: suppress unused variable 'e' warning

Patch by cosmo0920. Thanks!!!
configure.ac: enclosed in double quote entirely

PATH=`brew --prefix gettext`"/bin:\$PATH"
PATH="`brew --prefix gettext`/bin:\$PATH"
     ^<---------------------|
Merge pull request #198 from cosmo0920/doc-configure-error-msg-OSX

configure.ac: add missing sphinx error message for OSX with Homebrew system

Patch by cosmo0920. Thanks!!!
Add account information on ConoHa
Use "OS X" form

Because "OS X" is used since 10.7.