Support of native functions when evaluating an expression

[Seddryck]

It should be really useful to have support for native functions when we're dealing with an expression in a predicate. The first value will be the column identifier then we'll have the classic list of native functions separeted by the pipe |. To differentiate this to the NCalc usage we'll use the optional (when not present NCalc will be supposed) scriptxml element.

<all-rows>
  <alias column-index="0">myDate</alias> <!-- optional -->
  <expression name="MyModifiedDate">
    <script language="native">
      myDate | utc-to-local(Brussels) | dateTime-to-date
    </script>
  </expression>
  <predicate name="IntegerDepId">
    <more-than or-equal="true">2019-01-01</more-than>
  </predicate>
</all-rows>

[Seddryck]

Beta available at https://ci.appveyor.com/project/Seddryck/nbi/builds/23824520/artifacts in 1.20.0-beta.166