Rana Ora Versions Save

1. Fixed bug related to ORA-24435 in multi-threaded scenario.
2. Moved OCISvcCtx from Srv to Ses to support bug fix.
3. Moved Ping method and Break method from Srv to Ses due to OCISvcCtx change.
4. Revised logging cfg for Ping method and Break method.
5. Removed doc.go import of gopkg.in which was causing build failures on Windows.

The method changes are breaking changes; therefore, a new version number is given to support gradual changes through the use of gopkg.in\rana\ora.v3.

• Removed ora.GetDrv() method
• Added ora.Register() method
• Added ora.OpenEnv() method accepting optional *ora.EnvCfg
• Revised signature of env.OpenSrv() method to accept required paramenter *ora.SrvCfg
• Revised signature of srv.OpenSes() method to accept required paramenter *ora.SesCfg
• Removed ora.Log field. Use ora.Cfg().Log.Logger instead.
• Added ora.Cfg().Log.Logger to accept a Logger interface.
• Revised logging configuration. ora.Cfg().Log contains many options to enable logging or disable logging of specific methods through out the ora driver. This requires ora.Cfg().Log.Logger to be set.
• Improved multi-threaded safety by adding mutex to Drv, Env, Srv, Ses, and Stmt.
• Renamed Rset.SetNumberScaless to Rset.SetNumberInt.
• Renamed Rset.NumberScaless to Rset.NumberInt.
• Renamed Rset.SetNumberScaled to Rset.SetNumberFloat.
• Renamed Rset.NumberScaled to Rset.NumberFloat.
• Made Stmt.Cfg filed unexported.
• Added methods SetCfg and Cfg to Stmt.
• Revised internal error handling to include caller info.
• Revised internal logging to include caller info.
• Revised documentation to reflect changes.