fixed bug 2394
Fix Bug number 2393
bug fix 2398
fixed bug 2395
code review for ritesh changes
Clean up of 'sessions.md' file.
Fixing typo in dodos problems.
Merge branch 'ritesh'
fixed check empty expression message
Merge branch 'master' into pradeep
Merge branch 'pradeep'
Bug fix to re-enable the equation box in the node editor of affected nodes when a node is deleted.
Merge branch 'master' of https://github.com/bvds/LaitsV3
Merge branch 'master' into jingxian2
Code review for renaming Undo button.