Removed ambiguous rules

e.g k+a+i should result କାଇ instead of କୈ.
n+T should result ନଟ instead of ଣ୍ଟ
n+D should result ନଡ instead of ଣ୍ଡ
added test case for ai

added test case
Merge pull request #315 from psubhashish/patch-8

Removed ambiguous rules
Merge pull request #333 from psubhashish/patch-10

Added test case for ai