More lenient reading and writing for ints and floats

Previously, int fields only accepted ints, and float fields only accepted floats. 
Now, these can be specified as strings, and will try to force convert to the correct type. 
Force conversion is done only when needed, to avoid large ints getting corrupted by converting to float and back to int. 

Fixes #99 and #108

Author: karimbahgat

shapefile.py

@@ -3,11 +3,11 @@
 Provides read and write support for ESRI Shapefiles.
 author: jlawhead<at>geospatialpython.com
 date: 2017/04/29
-version: 1.2.11
+version: 1.2.12-dev
 Compatible with Python versions 2.7-3.x
 """
 
-__version__ = "1.2.11"
+__version__ = "1.2.12-dev"
 
 from struct import pack, unpack, calcsize, error, Struct
 import os
@@ -522,11 +522,19 @@ def __record(self):
                         #not parseable as float, set to None
                         value = None
                 else:
+                    # force to int
                     try:
-                        value = int(value)
+                        # first try to force directly to int.
+                        # forcing a large int to float and back to int
+                        # will lose information and result in wrong nr.
+                        value = int(value) 
                     except ValueError:
-                        #not parseable as int, set to None
-                        value = None
+                        # forcing directly to int failed, so was probably a float.
+                        try:
+                            value = int(float(value))
+                        except ValueError:
+                            #not parseable as int, set to None
+                            value = None
             elif typ == 'D':
                 # date: 8 bytes - date stored as a string in the format YYYYMMDD.
                 if value.count(b('0')) == len(value):  # QGIS NULL is all '0' chars
@@ -945,8 +953,18 @@ def __dbfRecords(self):
                     if value in MISSING:
                         value = str("*"*size) # QGIS NULL
                     elif not deci:
+                        # force to int
+                        try:
+                            # first try to force directly to int.
+                            # forcing a large int to float and back to int
+                            # will lose information and result in wrong nr.
+                            value = int(value) 
+                        except ValueError:
+                            # forcing directly to int failed, so was probably a float.
+                            value = int(float(value))
                         value = format(value, "d")[:size].rjust(size) # caps the size if exceeds the field size
                     else:
+                        value = float(value)
                         value = format(value, ".%sf"%deci)[:size].rjust(size) # caps the size if exceeds the field size
                 elif fieldType == "D":
                     # date: 8 bytes - date stored as a string in the format YYYYMMDD.