Default sensors.conf is fat and confusing

[khali]

The default sensors.conf file is very large now (2450 lines, 70 kB). This has a bad impact on performance. Compared to a custom configuration file for a specific motherboard, libsensors initialization is more than 5 times slower.

On top of that, many statements in the default configuration file are specific to a few motherboard models, or correspond to recommendations which motherboard manufacturers may or may not follow. This can be confusing for new users, which expects displayed labels to be correct.

I suggest that we strip down sensors.conf.eg to only include labels which we know are always correct (e.g. internal voltage labels.) There aren't that many so this should lead to a reasonably-sized default configuration file. Recommended wirings and scaling factors should be documented in a different place (kernel tree? wiki? man page?)

[khali]

In r5534, I moved the documentation header to sensors.conf.5, shaving approximately 250 lines off sensors.conf.eg. This is just a start, of course.

[khali]

New default configuration file: sensors.conf.default (r5603). With this one, "sensors" is approximately twice as fast as with sensors.conf.eg. The parsing of the configuration file itself is about 3.5 as fast as before.

[khali]

We now install sensors.conf.default instead of the fat sensors.conf.eg by default (r5605). Distributions are free to package sensors.conf.eg as documentation for reference.