Fix dd ambiguity; fix windbg commands on Python27

pwndbg/commands/shell.py

@@ -18,7 +18,6 @@ shellcmds = [
     "clear",
     "cp",
     "date",
-    "dd",
     "diff",
     "egrep",
     "find",

pwndbg/commands/windbg.py

@@ -56,7 +56,7 @@ def dX(size, address, count, to_string=False):
         except gdb.MemoryError:
             break
 
-    n_rows = math.ceil(count * size / float(16))
+    n_rows = int(math.ceil(count * size / float(16)))
     row_sz = int(16 / size)
     rows   = [values[i*row_sz:(i+1)*row_sz] for i in range(n_rows)]
     lines  = []