Field_CheckboxList: new setColumns
Field_Money: new setDigits
Field_ValueList: fix loadPOST

When checked Empty Text and also some other value checkboxes, then received string was like this 'A,B,C,' (ending with comma, because EmptyText value is empty string).
We better remove this not needed comma. Used trim and not rtrim to be sure that all commas will be removed.
Field_Number: fix validation if no value set
Field_Checkbox: new setValues
Field_Number: new setRange + validation

moved here from Field_Slider, because this could be useful for all numeric input fields
Field_Slider: new setLabels, extend Field_Number

Logically Slider should extend Field_Number and it's validation etc.
Field_Text: new setRows
Field_Slider: new setStep
Field_Slider: table width fix
Merge pull request #257 from DarkSide666/patch-15

Multiple fixes and extension for Form Fields