test: add test case for optimized between specify outside of key range
Support vector column delimiter change as experimental feature

TODO: write document about mroonga_vector_column_delimiter variable.
Merge pull request #15 from naoa/test-between-over-case

test: add test case for optimized between specify outside of key range

Patch by Naoya Murakami. Thanks!!!
Merge pull request #16 from naoa/add-server-variable-for-vector-delimiter

Support vector column delimiter change as experimental feature

Patch by Naoya Murakami. Thanks!!!