usql update

usql/Readme.md

@@ -1,10 +1,14 @@
 
 ### TODO
-- support for *
-- support for order by, offset, limit
-- add pipe | token
+- coalesce, date functions now, add_date; string functions rtrim, ltrim, rpad, lpad; math function round
+- add pipe | concatenation
+
+- support for order by, offset, limit (allow column name in order by, validate)
+- support for uniqueue indexes (primary key)
+- support for btree indexes
+- support for joining
 - add count min and max functions, eg aggregate functions
-- maybe to create iterator on table
-- add exceptions and rename it to UsqlException
-- class members should have prefix m_
+
 - add const wherever should be
+- PERF in Row::Row(const Row &other), could be more efficient (memory and cpu)
+- use references where pointer cannot be nullptr