Formalize and test treatment of whitespace

[Dominic Martinez]

Officially, Ham follows Jam's tokenization procedure where everything is separated by whitespace, except variables which are single tokens:

# valid Jam
if ! a && ( b = c ) {
  Echo [ on target return $(X:D) ] ;
}
# Removing/adding whitespace between _anything_ here changes the meaning of the program

Unofficially, Ham's parsing mechanism makes most whitespace optional, and can trivially enforce/remove whitespace requirements:

# (possibly) valid Ham
if !a&&(b=c){Echo[on target return $( X : D )];}
# Whitespace can be added/removed between semantic objects (except keywords) without consequence
# if they would not be interpreted as a single leaf

Currently, unit tests only cover the Jam-compatible language definition.

Ham should formalize its treatment of whitespace in the language specification, and then add unit tests to ensure compliance before users rely on this feature.

[Dominic Martinez]

Ham v2 has been moved; closing issues not relevant for v1.