COMP: Fix overloaded virtual warnings with VTKv6

Explicitly use base class implementations of transform overloads
operating on 'float' (which cast and call the double overloads, and so
will call the appropriate derived code) in order to avoid hiding the
overloads in the derived class. (Fixes -Woverloaded-virtual warnings.)

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23316 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Remove gratuitous virtual

Remove 'virtual' specifier of private classes in source files where said
classes are not and (due to being in a source file) never will be
derived. This avoids needing an explicit (virtual) dtor in order to
avoid a -Wnon-virtual-dtor warning.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23317 3bd1e089-480b-0410-8dfb-8563597acbee
STYLE: Fix spelling error in comment

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23318 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Don't stop uninstall on first error

Change how we process scheduled extension uninstall operations to
continue trying to uninstall all extensions, rather than stopping the
process after the first error. The old behavior is a result of operand
order to the '&&' operator, which employs short-circuit evaluation to
skip evaluation of the second argument (the call to uninstall the
extension) if the first argument (the overall result 'accumulator') is
false, and was likely unintentional, due to overlooking the short
circuit evaluation.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23319 3bd1e089-480b-0410-8dfb-8563597acbee