support partially specified custom primary key (go-rel#89)

Use context to manage transaction (go-rel#76)

* use context to determine transaction state

* updated reltest

* update docs transaction

* remove duplicated quick example and improve full example

* update copy

* fix test

* revert index

[doc] Mutations (go-rel#67)

* renamed query to queries

* fix links

* added mutations doc

* simplify crud

* fix pagination

* uncommit

delete all only accepts query chain (go-rel#53)

* delete all only accepts query chain

* remove unnecessary close before return

Fix: update not found when updating unchanged record (go-rel#39)

* update not found spec

* fix mysql driver

fix docs example and add missing reltest.New method (go-rel#27)

* fix docs example and add missing reltest.New method

* better example, test main function

* use New in tests

[doc] transactions (go-rel#23)

* added transaction

* add breakline

* added ga