Added descriptive error codes for both client and server errors in the module errorcode. A new sub-package locales has been added, which currently only supports English client error messages.

For example, errorcode.CR_CONNECTION_ERROR is 2002.

Added SQLMode class in the constants module to make it easier to set modes. For example:

cnx.sql_mode = [SQLMode.REAL_AS_FLOAT, SQLMode.NO_ZERO_DATE]