Various fixes for R CMD check. The argument order for sqlCreateTable() methods avoiding weird argument mismatch problems (#448). Fixed truncation when retrieving unicode data stored in VAR/CHAR columns (@detule, #553). Fixed issue related to fetching zero rows (@detule, #528). Backend specific improvements: MYSQL: Fixed retrieving results from stored procedures (@detule, #435). Oracle: performance enhancements (#577) Spark: Changed data type for date-times from DATE to TIMESTAMP (@schuemie, #555).
