isa module added, some bugfixes

'isa.o' is roughly what was called 'sensor.o' in doc/design.


git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@12 7894878c-1315-0410-8ee3-d5d059ff63e0

doc/design

@@ -7,6 +7,8 @@ Document version 1.0, 19981101.
                  1.1, 19981111.
                  1.2, 19981118.
 
+--> Never, ever change the driver struct with this technique! 
+
 
 Object oriented approach
 ========================
@@ -168,7 +170,7 @@ included in kernels around 1.2.120!).
 A driver
 --------
 
-struct sensor_driver {
+struct i2c_driver {
   char name[32];
   int id;
   unsigned int flags;