Release Name: 0.9.0

Notes:
Ruby/groonga is a extension library to use groonga's DB-API
layer. Ruby/groonga provides Rubyish readable and writable
API. You can use groonga's first and highly functional
features from Ruby.


Changes:
* Supported groonga 0.1.5
* Added API
  * Groonga::Object#context
  * Groonga::Record#n_sub_records
  * Groonga::Context#send
  * Groonga::Context#receive
  * Groonga::PatriciaTrie#prefix_search [Tasuku SUENAGA]
  * Groonga::Object#path [Ryo Onodera]
  * Groonga::Object#lock [Tasuku SUENAGA]
  * Groonga::Object#unlock [Tasuku SUENAGA]
  * Groonga::Object#locked? [Tasuku SUENAGA]
  * Groonga::Object#temporary?
  * Groonga::Object#persistent?
  * Groonga::ObjectClosed
  * Groonga::Context.[]
  * Groonga::Table#column_value
  * Groonga::Table#set_column_value
* Changed API
  * Groonga::Table#select, Groonga::Column#select
    * They also accept Groonga::Expression
    * Added :syntax option that specifies grn expression syntax
  * Groonga::Table#open_cursor
    * Added :offset option that specifies offset.
    * Added :limit option that specifies max number of records.
  * Changed Groonga::Expression.parse options:
    * (nil (default) -> :column) -> (nil (default) -> :query)
    * :column -> removed
    * :table -> :query
    * :table_query -> :query
    * :expression -> :script
    * :language -> :script
  * Groonga::Table#define_column, Groonga::Table#define_index_column
    * Defined column becomes persistent table by default
  * Groonga::Table#[] -> Groonga::Table#value
  * Groonga::Table#[]= -> Groonga::Table#set_value
  * Groonga::Table#find -> Groonga::Table#[]
  * Groonga::Table#find -> obsolete
  * Groonga::Table#[]= -> removed
  * Groonga::TableKeySupport#[]= is alias of Groonga::TableKeySupport#add
  * Changed exception class to Groonga::NoSuchColumn from
    Groonga::InvalidArgument when Groonga::Record accesses nonexistent
    a column.
* Bug fixes
  * Fixed a bug that context isn't passed to schema [dara]
  * Fixed a bug that Groonga::PatriciaTrie#tag_keys doesn't return
    that last text.
    [Ryo Onodera]
* Added --with-debug option to extconf.rb for debug build.
* Fixed a bug that Ruby 1.9.1 may fail extconf.rb.

=== Thanks

* dara
* Ryo Onodera
* Tasuku SUENAGA