support POD type
some basic types
add list & vector
add more include
Add custom struct test
fix type & length function
Demo. No debugging.
Fix sth. Can run the test now.
Fix sth.
Merge remote-tracking branch 'pondering/serialization' into merge_hetero_and_serial
Enable Serialization
Remove unnecessary codes. Add default type.
add 3 api: parse and update and data_type_name
merge heterogenous
using convert_to_string. dont copy code.
BUgs fixed. Change Writer API to keep consistent. Enable typename query. Engine done.
merge from heterogeneous