Add row limiting clause for select statement

[lm-net]

Hello Felipe, I've just found your project and it's excellent piece of work. Unfortunately, I'm missing row limiting clause as described here https://docs.oracle.com/database/121/SQLRF/statements_10002.htm#BABBADDD

So, I tried to implement it

• Added OFFSET, PERCENT, TIES keywords
• Added new clauses for SELECT expression - ROW_LIMITING_CLAUSE (composed from OFFSET_CLAUSE, FETCH_ROW_CLAUSE)
• Implemented ROW_LIMITING_CLAUSE into SELECT statement
• Added unit test for row limiting clause

Honestly, I'm using GIT for the first time, so just let me know, if there are any problems.

EDIT: I've found small error - row limiting clause could be used without order by clause.

[lm-net]

Hi Felipe, thanks for finding the error. I tried to fix it and added 2 new test cases for select statement.

I hope, I've managed to merge this branch with master correctly (I'm new to GIT, so I'm still learning how to use it).