Add --with-udev[=PATH] to configure script, for non-SUID root operation

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

When light is installed in the non-SUID root mode it cannot write to
/etc/light anymore, so we set up a ~/.cache/light instead.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

This patch adds support for installing the 90-backlight.rules to gain
privileges to the kernel sysfs files.  By default the classic SUID root
mode is used and the rules file is not installed.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Add Fedora installation instructions

Coding style

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Misc

- Use version from configure script
- Simplify usage text for accessibility, only one command at a time
- Simplify terminology, we have commands and options to commands

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Most users want to see the examples as early as possible, so we place
them directly after the new (simplified) introduction.  The examples
have been rewritten to separate commands from options and grouping
the command with its value, where applicable.

The rest of the document has just been auto-filled to fit to < 72
columns and sections now use === and ---- for headings to make the
README more accessible from a terminal.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Unused file.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Convert build system to GNU configure & build

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Add proper light.1 man page, removes help2man dependency

Better Support for Overriding Install Prefix

Address #27

This patch adds a standard configure script and converts the Makefile to
automake.  This adresses PR #30, but in a more generic way, and also
eliminates the hard coded CC variable, enabling building with clang or
even a cross compiler.

Note: this is more a proof of concept and does not include the man page
      generation.  Another pull request addresses that.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Fix save and restore arguments

By not always appending "/usr" to the path, it enables install into /usr/local
and better integration with tools like stow.

Without this patch -O and -I are not supported anymore and lead to an
error.

Various fixes and improvements

- Use NAME_MAX and PATH_MAX instead of hardcoded values
- Allow paths to be longer than 256 chars
- Check pointers everywhere
- Use strncpy/snprintf instead of strcpy/sprintf
- Validate controllers' name (-s flag + a very long name -> bad things happening)
- Get rid of globals for dir iteration

- Rewrite of all clamp operations
- Get rid of unreachable code (the 'else' in the last chunk)

Also add more examples

Now we can save, restore, get [max] brightness etc. for both screen
and keyboard controllers