Import buffer module
Backup. Basic function of insert, create, select added. Some util functions added.
Add record class provide pack&unpack for records. Changes on evaluator and others.
Backup. Minor bugs fixed.
Updaate gitignore and buffer module
Add record manager
Add trash file
rename file.
Merge 'record' into 'master', wait to combine all moduels and debug.'
Merge branch 'evaluator'