Rename m and z range attributes

Rename Reader attributes from "measure" and "elevation", to "mbox" and "zbox". More clear that refers to min/max values, and parallels the names used in the Writer class.

Author: karimbahgat

README.md

@@ -99,6 +99,7 @@ Users of the previous version 1.x should therefore take note of the following ch
   - More convenient accessing of Record values as attributes. [@philippkraft]
   - More convenient shape type name checking. [@megies] 
 - Add more support and documentation for MultiPatch 3D shapes. 
+- The Reader "elevation" and "measure" attributes now renamed "zbox" and "mbox", to make it clear they refer to the min/max values. 
 - Better documentation of previously unclear aspects, such as field types. 
 
 ### Important Fixes:
@@ -893,7 +894,7 @@ Shapefiles containing M-values can be examined in several ways:
 
 	>>> r = shapefile.Reader('shapefiles/test/linem')
 
-	>>> r.measure # the lower and upper bound of M values in the shapefile
+	>>> r.mbox # the lower and upper bound of M values in the shapefile
 	[0.0, 3.0]
 
 	>>> r.shape(0).m # flat list of M values
@@ -926,7 +927,7 @@ To examine a Z-type shapefile you can do:
 
 	>>> r = shapefile.Reader('shapefiles/test/linez')
 
-	>>> r.elevation # the lower and upper bound of Z values in the shapefile
+	>>> r.zbox # the lower and upper bound of Z values in the shapefile
 	[0.0, 22.0]
 
 	>>> r.shape(0).z # flat list of Z values

changelog.txt

@@ -18,6 +18,7 @@ VERSION 2.0.0
 	  - More convenient accessing of Record values as attributes. [@philippkraft]
 	  - More convenient shape type name checking. [@megies] 
 	* Add more support and documentation for MultiPatch 3D shapes. 
+	* The Reader "elevation" and "measure" attributes now renamed "zbox" and "mbox", to make it clear they refer to the min/max values. 
 	* Better documentation of previously unclear aspects, such as field types. 
 
 	Bug Fixes:

shapefile.py

@@ -701,15 +701,15 @@ def __shpHeader(self):
         # The shapefile's bounding box (lower left, upper right)
         self.bbox = _Array('d', unpack("<4d", shp.read(32)))
         # Elevation
-        self.elevation = _Array('d', unpack("<2d", shp.read(16)))
+        self.zbox = _Array('d', unpack("<2d", shp.read(16)))
         # Measure
-        self.measure = []
+        self.mbox = []
         for m in _Array('d', unpack("<2d", shp.read(16))):
             # Measure values less than -10e38 are nodata values according to the spec
             if m > NODATA:
-                self.measure.append(m)
+                self.mbox.append(m)
             else:
-                self.measure.append(None)
+                self.mbox.append(None)
 
     def __shape(self):
         """Returns the header info and geometry for a single shape."""