Whitespace preservation

[forivall]

• Create CST when parsing
• Add CST elements to Javascript AST
• Create a generator that creates a CST (fork tacotruck -> taqueria) #20 - Create tacoscript generator that is CST aware
• Create cst-aware js generator (fork babel-generator -> alpastor) #21 - Create javascript generator that is CST aware
• Preserve CST in transforms
  • first, manually in transforms - helpers in comal-types to set CST data
  • second, automatically in comal-traverse - place whitespace from nodes removed in "replaceWith" into their replacement nodes.
• Analyse source CST and when converting to translated CST, try to use most commonly used pattern for given node pattern