replace 32bit mersenne twister with pcg

and added bounds argument for rand and num rand.
See GH #99

But it is 6.8% slower than mt:
3m11.529s vs 2m58.521s for binarytrees.pn

ChangeLog

@@ -5,6 +5,8 @@ v0.4
         * Fix installation from source without git
         * Fixed various SEGVs and minor errors and security issues.
         * Fixed cmp for string (Peter Arthur)
+        * Replaced 32bit mersenne twister with pcg.
+        * Added bounds argument for rand and num rand.
 
 v0.3	Sat Oct 17 10:42:49 CEST 2015 rurban v0.3-g7963cbc-1264
 

Makefile

@@ -4,7 +4,7 @@
         examples release install grammar doxygen website testable
 .NOTPARALLEL: test
 
-SRC = core/asm.c core/ast.c core/compile.c core/contrib.c core/gc.c core/internal.c core/lick.c core/mt19937ar.c core/number.c core/objmodel.c core/primitive.c core/string.c core/syntax.c core/table.c core/vm.c
+SRC = core/asm.c core/ast.c core/compile.c core/contrib.c core/gc.c core/internal.c core/lick.c core/pcg.c core/number.c core/objmodel.c core/primitive.c core/string.c core/syntax.c core/table.c core/vm.c
 PLIBS = readline buffile aio database
 PLIBS_SRC = lib/aio.c lib/buffile.c lib/database.c lib/readline/readline.c lib/readline/linenoise.c
 GREGCFLAGS = -O3 -DNDEBUG
@@ -202,7 +202,7 @@ $(foreach o,${OBJS},core/internal.${o} ): core/internal.c core/potion.h core/con
 $(foreach o,${OBJS},core/lick.${o} ): core/lick.c core/potion.h core/config.h core/internal.h
 $(foreach o,${OBJS},core/load.${o} ): core/load.c core/potion.h core/config.h core/internal.h \
  core/table.h core/khash.h
-$(foreach o,${OBJS},core/mt19937ar.${o} ): core/mt19937ar.c core/potion.h core/config.h
+$(foreach o,${OBJS},core/pcg.${o} ): core/pcg.c core/potion.h core/config.h
 $(foreach o,${OBJS},core/number.${o} ): core/number.c core/potion.h core/config.h core/internal.h
 $(foreach o,${OBJS},core/objmodel.${o} ): core/objmodel.c core/potion.h core/config.h core/internal.h \
  core/khash.h core/table.h core/asm.h

core/number.c

@@ -469,7 +469,7 @@ void potion_num_init(Potion *P) {
   potion_method(dbl_vt, "/", potion_dbl_div, "value=D");
   potion_method(dbl_vt, "abs", potion_dbl_abs, 0);
   potion_method(dbl_vt, "cmp", potion_dbl_cmp, "value=D");
-  //potion_method(dbl_vt, "rand", potion_dbl_rand, 0);
+  //potion_method(dbl_vt, "rand", potion_dbl_rand, "|bound=D");
   // optimized integer-only methods, for both operands
   potion_method(int_vt, "+", potion_int_add, "value=I");
   potion_method(int_vt, "-", potion_int_sub, "value=I");
@@ -482,7 +482,7 @@ void potion_num_init(Potion *P) {
   potion_method(int_vt, "chr", potion_int_chr, 0);
   potion_method(int_vt, "abs", potion_int_abs, 0);
   potion_method(int_vt, "cmp", potion_int_cmp, "value=I");
-  //potion_method(int_vt, "rand", potion_int_rand, 0);
+  //potion_method(int_vt, "rand", potion_int_rand, "|bound=I");
   potion_method(num_vt, "step", potion_int_step, "end=N,step=N,block=&");
   potion_method(num_vt, "times", potion_int_times, "block=&");
   potion_method(num_vt, "to",   potion_int_to, "end=N,block=&");

core/objmodel.c

@@ -748,7 +748,7 @@ void potion_lobby_init(Potion *P) {
   potion_method(P->lobby, "kind",  potion_lobby_kind, 0);
   potion_method(P->lobby, "isa?",  potion_lobby_isa, "value=o");
   potion_method(P->lobby, "srand", potion_srand, "seed=N");
-  potion_method(P->lobby, "rand",  potion_rand, 0);
+  potion_method(P->lobby, "rand",  potion_rand, "|bound=N");
   potion_method(P->lobby, "self",  potion_lobby_self, 0);
   potion_method(P->lobby, "string", potion_lobby_string, 0);
   potion_method(P->lobby, "can",   potion_lobby_can, "method=S");