Add mod(x,y) function to r.mapcalc and r3.mapcalc doc (#1617)

* Add mod(x,y) function to r.mapcalc doc

* Add mod(x,y) function to r3.mapcalc doc

* Add mod(x,y) to r.mapcalc wx functions list

gui/wxpython/modules/mcalc_builder.py

@@ -106,6 +106,7 @@ class MapCalcFrame(wx.Frame):
             "max(x,y[,z...])": "max( , )",
             "median(x,y[,z...])": "median( , )",
             "min(x,y[,z...])": "min( , )",
+            "mod(x,y)": "mod( , )",
             "mode(x,y[,z...])": "mode( , )",
             "nmax(x,y[,z...])": "nmax( , )",
             "nmedian(x,y[,z...])": "nmedian( , )",

raster/r.mapcalc/r.mapcalc.html

@@ -359,6 +359,7 @@ log(x,b)                log of x base b                                 F
 max(x,y[,z...])         largest value of those listed                   *
 median(x,y[,z...])      median value of those listed                    *
 min(x,y[,z...])         smallest value of those listed                  *
+mod(x,y)                return the modulus (the remainder) of x/y       *
 mode(x,y[,z...])        mode value of those listed                      *
 nmax(x,y[,z...])        largest value of those listed, excluding NULLs  *
 nmedian(x,y[,z...])     median value of those listed, excluding NULLs   *

raster/r.mapcalc/r3.mapcalc.html

@@ -224,6 +224,7 @@ log(x,b)                log of x base b                                 F
 max(x,y[,z...])         largest value of those listed                   *
 median(x,y[,z...])      median value of those listed                    *
 min(x,y[,z...])         smallest value of those listed                  *
+mod(x,y)                return the modulus (the remainder) of x/y       *
 mode(x,y[,z...])        mode value of those listed                      *
 nmax(x,y[,z...])        largest value of those listed, excluding NULLs  *
 nmedian(x,y[,z...])     median value of those listed, excluding NULLs   *