TableInfo.java coding complete.

Small change in MyEnv.java
1) add close db method
2) rename class and method names

SQLParser.jj modified at exception handling point.
- Before : Program stop when catch exception
- After : Non-stop but remain in process.
	1) If syntax error occured(TokemMgrError, ParseException), reinitiate myParser instance and get inputstream again.
	2) If SQL exception occured(SQLException, DatabaseException), stop present parsing query and go to next query.
complete before drop table !! (create, primary, reference, desc, show tables ok)
project 1-2 handin version
project 1-2 submit
- add referential constarint error in drop table query,
project 1-2 after submit modification
1) descDB : show database key/value records
2) SQLParser.jj
 (1) modify all referencing pointer method
 (2) modify some variables
 (3) drop table modify : to reflect cascading deletion
3) MyEnv.java
 accordance with 2)-(3), modify removeDb method