Add spaces to color parsing

[cwervo]

Yeah, I guess other alternatives to Wish this is outlined rgb([* $i 10],0,0) are:

• support spaces & tell people to use quotation marks if using them (or braces if not interpolating)Wish this is outlined > "rgb([* $i 10], 0, 0)"
• move away from css syntax and use tcl Wish this is outlined [rgb [* $i 10] 0 0]

Neither seems like an unqualified win to me :-/

Originally posted by @osnr in #134 (comment)

[osnr]

Random idea: we could add support for 'custom readers' that When and Claim and Wish invoke that can consume multi-term expressions like rgb(1, 2, 3)