Double-space reguired around infix function calls

This release is mostly a change to the parser to handle whitespace in a uniform way.

The major change that is that the infix function-calling syntax requires two spaces around the function name. For example note the two spaces around str below:

    greeting := "Hello "
    name := "Eamonn"
    greeting  str  name

=> "Hello Eamonn"

which is equivalent to

    greeting := "Hello "
    name := "Eamonn"
    str(greeting,  name)

=> "Hello Eamonn"