Feature #16: Advanced window matching

- Add advanced window matching system, capable of matching against
  arbitrary window properties as well as a series of internal
  properties, with 4 additional operators (>, <, >=, <=) useful for
  integer targets, and support of logical operators. The old matching
  system is removed, but compatibility with the format is retained.

- As the new matching system is pretty complicated, and I have no past
  experience in writing a parser, it's pretty possible that bugs are
  present. It also has inferior performance, but I hope it doesn't
  matter on modern CPUs.

- It's possible to disable matching system at compile time with NO_C2=1
  now.

- Add ps->o.config_file to track which config file we have actually
  read. Queryable via D-Bus.

- Parse -d in first pass in get_cfg() as c2 needs to query X to get
  atoms during condition parsing.

- Fix a bug in wid_get_prop_adv() that 0 == rformat is not handled
  correctly.

- Fix incompatibility with FreeBSD sed in dbus-examples/cdbus-driver.sh
  .

- Add recipe to generate .clang_complete in Makefile, used by Vim
  clang_complete plugin.

- Add DEBUG_C2 for debugging condition string parsing. DEBUG_WINMATCH is
  still used for match debugging.

- Rename win_on_wdata_change() to win_on_factor_change().

- Extra malloc() failure checks. Add const to matching cache members in
  session_t. Code clean-up. Documentation update.
Merge branch 'master' into richardgv-dev

Conflicts:
	src/compton.c
Improvement: Improve color inversion performance & Validate pixmap

- Try to improve the performance of color inversion by applying clipping
  region during color inversion. (#75)

- Validate pixmap on window unmap/destruction. Probably slightly helpful
  for #52.

- Change the design of unmap_win() and destroy_win(), a bit.

- Add warning message to help messages about features disabled at
  compile time, instead of dropping their description completely. (#85)

- Silence some warnings. Code clean-up.
Improvement #7: Add GLX_OML_sync_control VSync support

- Add "vsync-oml" VSync method, using GLX_OML_sync_control. Untested,
  because it's not supported by my driver.

- Unredirect ps->reg_win, because DRI wiki says it's related to the
  behavior of OpenGL VSync extensions.

- Add glFlush() and glXWaitX() calls, in hope they are slightly helpful
  for VSync.

- Change a few functions to make error handling more graceful. Make some
  errors fatal. Code clean-up.

- Add unused function make_text_prop().
Improvement: Change VSync mode with D-Bus & Makefile update & Misc

- Add on-the-fly VSync option modification via D-Bus, as requested by
  kunitoki (#80). Expose parse_vsync(), create vsync_init() and
  ensure_glx_context().

- Change default value of ps->drm_fd to -1.

- Update Makefile. Change the install/uninstall rules and add doc
  installation, requested by hasufell in #85.

- Mark window not damaged in map_win(). It helps in reducing flickering
  with inverted window color, but I'm not completely sure if it's safe.

- Avoid modifying w->invert_color when window is unmapped.

- Update documentation. Thanks to hasufell for pointing out.
Misc #86: Compatibility with BSD install

- Make Makefile compatible with BSD install, by dropping -D.

- Make CFG independent in Makefile, to allow people to specify CFLAGS
  as a parameter to make.

- Correct location of .clang_complete.