small fix: file preview IF NOT new

show file preview only if file is not new
modified getInputName / getInputId

those functions have been moved to an upper level, to allow access to
other sublasses other than only the "input" class.
They also have been modified to work even if the domId and domName
variable are assigned
adapting and cleaning of input file

The input file has been modified to work with the new getInputId and
getInputName functions.
the JS code has been moved out from the input itself.
Modified form label rendering

the form label rendering subclass has been modified to render other
markup than just a <label> tag