check whether storage is null before searching
modify names:
Merge branch 'master' of https://github.com/cs2103aug2014-w13-4j/main into chuyu-storage
minor changes for format and small bugs
resolve merge conflict
minor modifications
Modify search and filter command
Remove extra fields
Add more param to update command
Separated task modifier into a separate class
Remove unused imports and constant
Merge branch 'xy-search-command' of github.com:cs2103aug2014-w13-4j/main into pn-logic
Search method in logic
Correct comment
fix bug in complete task
Add test for complete task with date
Implemented conditional dates in the form of a pair of start date and due date
Merge branch 'pn-modify-conditional-task' of https://github.com/cs2103aug2014-w13-4j/main into chuyu-storage
Add append function for conditional dates
add in tree set to map task attributes