add simple docs and use namespaced tc::solve

include/groups.h

@@ -39,24 +39,54 @@ namespace tc {
     Group schlafli(const std::vector<int> &mults);
 
     namespace group {
+        /**
+         * Simplex
+         */
         Group A(int dim);
 
+        /**
+         * Cube, Orthoplex
+         */
         Group B(int dim);
 
+        /**
+         * Demicube, Orthoplex
+         */
         Group D(int dim);
 
+        /**
+         * E groups
+         */
         Group E(int dim);
 
+        /**
+         * 24 Cell
+         */
         Group F4();
 
+        /**
+         * Hexagon
+         */
         Group G2();
 
+        /**
+         * Icosahedron
+         */
         Group H(int dim);
 
+        /**
+         * Polygonal
+         */
         Group I2(int n);
 
+        /**
+         * Toroidal. I2(n) * I2(m)
+         */
         Group T(int n, int m);
 
+        /**
+         * Toroidal. T(n, n)
+         */
         Group T(int n);
     }
 }