refactor: prepare for boolean functions

* Defines a BooleanT type
  * adds options to the Type constructor, so far just to allow conversions
    from other types
  * renames Number type to NumberT
  * records the name of types, and puts the name in the string representation
  * defines a conversion fron BooleanT to NumberT, specified to be automatic
  * stub code for automatic conversions, not yet complete
  * BooleanT not yet added to nanomath

Checked that the new facilities do not disrupt the prior behavior on numbers.

src/package.json

@@ -1,6 +1,7 @@
 {
     "imports" : {
         "#nanomath": "./nanomath.js",
+        "#boolean/*.js": "./boolean/*.js",
         "#core/*.js": "./core/*.js",
         "#number/*.js": "./number/*.js"
     },