Fix 2 segfault issues (function call without params + some functions like (a+b+c) )

Author: gre

btree.c

@@ -37,6 +37,7 @@ BoolNode* btree_newLeaf(int b) {
 
 int btree_equals(BoolNode* a, BoolNode* b) {
   if(a==0) return (b==0);
+  if(b==0) return FALSE;
   if(a->left==0) return b!=0 && b->left==0 && a->val == b->val;
   return btree_equals(a->left, b->left) && btree_equals(a->right, b->right);
 }

interpreter.c

@@ -299,7 +299,7 @@ extern TPA_Expr* pa_newCall(char* s, TPA_Expr** params) {
     strcpy(cpy, s);
     t -> type = TPA_CALL;
     t -> call = cpy;
-    t -> point = TPAExpr_toPoint(params);
+    t -> point = (params==0) ? point_init(0) : TPAExpr_toPoint(params);
     return t;
 }
 

point.c

@@ -7,7 +7,7 @@
 Point point_init(int dim) {
   Point p;
   p.dim = dim;
-  p.vect = (Bool*)calloc(dim, sizeof(Bool));
+  p.vect = dim==0 ? 0 : (Bool*)calloc(dim, sizeof(Bool));
   return p;
 }