Clarify licensing

README.markdown

@@ -5,8 +5,11 @@ This library contains components commonly used in designing and moching up
 mechanical designs. It is currently unfinished and you can expect some API
 changes, however many things are already working.
 
-This library is licensed under the LGPL 2.1
-See http://creativecommons.org/licenses/LGPL/2.1/ or the included file, lgpl-2.1.txt.
+This library was created by various authors as named in the individual
+files' comments. All the files except those ThingDoc are licensed under
+the LGPL 2.1 (see http://creativecommons.org/licenses/LGPL/2.1/ or the
+included file lgpl-2.1.txt), some of them allow distribution under more
+permissive terms (as described in the files' comments).
 
 ## Usage ##
 

constants.scad

@@ -1,5 +1,5 @@
 // MIT license
-
+// Author: Elmo Mäntynen
 
 TAU = 6.2831853071; //2*PI, see http://tauday.com/
 PI = TAU/2;

lego_compatibility.scad

@@ -1,9 +1,9 @@
 // This file is placed under the public domain
 
 // from: http://www.thingiverse.com/thing:9512
+// Author: nefercheprure
 
-
-// EXAMPLES:
+// Examples:
 //   standard LEGO 2x1 tile has no pin
 //      block(1,2,1/3,reinforcement=false,flat_top=true);
 //   standard LEGO 2x1 flat has pin