String to Number robustness

Dear KNIMErs,

It's me again. Another littel bug I found: String to Number can handle trailing blanks when set to double, while being set to int it complains about these same values. So currently I'm chaining String to Number with Double to Int, but you will admit that it's a nuisance, won't you? :-)

Oh, and having the "String to Date" interface match with "String to Number" (i.e. in allowing column multi-select) would avoid another set of ugly chains in timeseries-heavy applications.

Thanks for considering this for 2.4 latest! ;-)