Add M+ and SPACES words.

Reorganize test suite alphabetically, add
several missing tests.

Execute one line of input at a time.

Author: Molorius

README.md

@@ -745,6 +745,7 @@ error if it cannot be cannot be cross compiled.
 * `S"`
 * `S>D`
 * `SPACE`
+* `SPACES`
 * `STATE`
 * `SWAP`
 * `THEN`
@@ -809,15 +810,20 @@ all can be in the future.
 * `2CONSTANT`
 * `2LITERAL`
 * `2VARIABLE`
-* `D-`
 * `D+`
+* `D-`
 * `D0<`
+* `D<`
 * `D0=`
 * `D>S`
 * `DABS`
 * `DMAX`
 * `DMIN`
 * `DNEGATE`
+* `M+`
+
+# Standard Double extension words
+
 * `DU<`
 
 # Optimizations

pkg/forth/builtin/03_double.f

@@ -5,6 +5,7 @@
 
 : DNEGATE 0. 2SWAP D- ;
 : DABS DUP 0< IF DNEGATE THEN ;
+: M+ S>D D+ ;
 
 : D= ( x1 x2 y1 y2 -- bool )
     ROT ( x1 y1 y2 x2 )

pkg/forth/builtin/10_print.f

@@ -25,6 +25,15 @@
 
 DEFER EMIT \ let us change EMIT
 : SPACE BL EMIT ;
+: SPACES ( n -- )
+    DUP 0> IF
+        0 DO
+            SPACE
+        LOOP
+    ELSE
+        DROP
+    THEN
+;
 : CR 10 13 EMIT EMIT ;
 
 : U.NOSPACE ( u -- )