ENH: ignore size specification for numeric types

ENH: TIME can be specified a size with PGSQL
BUG: no size for usual numeric types with PGSQL

     specification in the form of a double instead of a singleton), but for
     now size is ignored for FLOAT and DOUBLE types with  MySQL.

     strings that are constructed with mixed string and integer types.

COMP: Move private implementation details out of vtkMySQLDatabase and into a PIMPL class, to eliminate errors compiling client-server wrappers.

     using += operator... use ostringstream.

     a case statement.
ENH: use vktStdString() instead of 0 for a really empty vtkStdString.

STYLE:Be more accurate about viewport coordinates. The range of coordinates [-1,+1],[-1,+1],[nearz,farz] is for points located inside the frustum.

COMP: Excluding (through preprocessor commands) classes and test that depend on Qt's SQL module for editions that do not contain it.  There is not currently a clean way to do this in CMake.

     INDEX creation within a CREATE TABLE statement: in this case,
     such INDEX creations are handled separately after all table creations
     have been done.
STYLE: some re-formatting and indenting

BUG: error copying edge attributes when using a vertex selection as input to vtkExtractSelectedGraph

     NB: 3 cases may occur: size unused, allowed or mandatory. In the
     latter case, if no size is provided, then a default value (#-defined)
     is assigned.
ENH: added minimal support for table preambles.
ENH: moved the GetColumnType methods to the internals of ExecuteSchema.
     This results in a smaller API, at the expense of a little flexibility.
ENH: refined support for various types at the concrete class level

COMP: Mask out two more frequently occurring Qt warnings. Eliminate unused variables to eliminate warnings.