Optimize persistence queue (#83) 

Fix supports for arrays in fields (#74) 

Unsized index space (#70) - support for `String`s in indexes for persistence

release 0.5.1 

release 0.5.0 

Version bump (#43) 

Add basic persistence feature (#13) - add generation of `Space` object that represents file that stores table's data - add `DatbaseManager` object that is used to control multiple tables - add methods for `Worktables` to use data in files. `persist` is used to save data to file. `load_from_file` is used to load table from file.

change `codegen` version 

Add upsert feature 

Add update generation