double are not correct, real are sql99,see deatils

investigating http://home.comcast.net/~jbondor/SQLNutshell/23SQL99AndVendorSpecificDatatypes.htm real must do not fail when install in mayor sql databases, **i tested that in postgresql (real and double work) and sqlite (real work)**, i do not have mysql, but i see in https://mariadb.com/kb/en/sql-99-complete-really/02-general-concepts/sql-data-types/ that this are sure work, with that solved definitively the #240 issue and closed #240 definitivelly ... please make tests **(tested and works for sqlite and postgres**, i could tested in oracle due limitation of resources)
Merge pull request #249 from mckaygerhard/master

double are not correct, real are sql99,see deatils