Update upgrade guide [wip] (#272)
Update upgrade guide [wip] (#272)

* Update upgrade guide with changes to testCommon

* -the

* has -> have

* fresh -> unique

* Better explanation on why cleanup code is no longer necessary

* location based -> disk-based

* Remove no longer relevant testCommon header

* Add note about removing errorValues() test

* Add note about removing snapshot() test

* Update note about test function signature

* Actually, scratch the header on test function signature

* single entry point

* add iterator.seek

* add collectEntries

* testCommon.js is gone -> testCommon is gone

* add chained batch

* remove removal of errorValues which we removed but also added

* serialization (wip)

* serialization (continued)

* add toc

* clarify that only an implementation with location should set this.location

* warn about type checks for location

* tweak test suite setup and wording (NYI)

* not stringified

Level/abstract-leveldown