Remove deprecated subplot 0

Author: jenshnielsen

lib/matplotlib/axes/_subplots.py

@@ -58,15 +58,10 @@ def __init__(self, fig, *args, **kwargs):
                 num = [int(n) for n in num]
                 self._subplotspec = GridSpec(rows, cols)[num[0] - 1:num[1]]
             else:
-                if num < 0 or num > rows*cols:
+                if num < 1 or num > rows*cols:
                     raise ValueError(
-                        "num must be 0 <= num <= {maxn}, not {num}".format(
+                        "num must be 1 <= num <= {maxn}, not {num}".format(
                             maxn=rows*cols, num=num))
-                if num == 0:
-                    warnings.warn("The use of 0 (which ends up being the "
-                                  "_last_ sub-plot) is deprecated in 1.4 "
-                                  "and will raise an error in 1.5",
-                                  mplDeprecation)
                 self._subplotspec = GridSpec(rows, cols)[int(num) - 1]
                 # num - 1 for converting from MATLAB to python indexing
         else: