Fix potential crashes found by ASan/Clang/GCC

--- openbor.c.orig	2016-12-22 13:02:02 UTC
+++ openbor.c
@@ -13933,7 +13933,7 @@ void generate_basemap(int map_index, flo
 
 void load_level(char *filename)
 {
-    char *buf;
+    char *buf = NULL;
     size_t size, len, sblen;
     ptrdiff_t pos, oldpos;
     char *command;
@@ -15210,6 +15210,11 @@ void bar(int x, int y, int value, int ma
         return;
     }
 
+    if (value < 0)
+    {
+        value = 0;
+    }
+
     if (value > maxvalue)
     {
         value = maxvalue;
@@ -20471,7 +20476,7 @@ void common_dot()
     entity     *eOpp;       //Owner of dot effect.
     s_collision_attack    attack;     //Attack struct.
 
-    for(iIndex = 0; iIndex <= MAX_DOTS; iIndex++)                                               //Loop through all DOT indexes.
+    for(iIndex = 0; iIndex < MAX_DOTS; iIndex++)                                                //Loop through all DOT indexes.
     {
         iDot_time   =   self->dot_time[iIndex];                                                 //Get expire time.
         iDot_cnt    =   self->dot_cnt[iIndex];                                                  //Get next tick time.