New sensors.conf keyword 'ignore'

This often-asked for, long-planned and somewhat-forgotten feature
makes it possible to tell libsensors-linked applications (like
the sensors program) that certain features should not be displayed.
This is very nice for things like unconnected temperature sensors
or fans.

Modifications to the library code, to the sensors program and to
the documentation and example sensors.conf file.


git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@676 7894878c-1315-0410-8ee3-d5d059ff63e0

etc/sensors.conf.eg

@@ -14,7 +14,7 @@
 # quotes operate like those in C.
 
 # A 'chip' line specifies what the following 'label', 'compute', 'set' and 
-# (not yet implemented) 'valid' lines refer to. In this case, until the
+# 'ignore' lines refer to. In this case, until the
 # next 'chip' line, everything refers to all lm78, lm78-j and lm79
 # chips. Other examples are *-isa-* for everything on the ISA bus, and
 # lm78-j-i2c-*-4e for all lm78-j chips on address 0x4e of any I2C bus.
@@ -101,10 +101,11 @@
 #set in0_max vid*1.05
 #set in0_min vid*0.95
 
-# Invalid statements tell certain features are not wanted. User programs can
+# Ignore statements tell certain features are not wanted. User programs can
 # still read them if they really want, though; this is just an advisory
 # marking. 'in0' would also invalidate 'in0_max' and 'in0_min'.
-# The invalid keyword is not yet recognized by the parser.
+#
+#ignore in0
 
 
 # There is one other feature: the 'bus' statement. An example is below.