doc: update doxygen configuration

Also add some boilerplate around.

Change-Id: Idbf21e1a1dad5c59475250db7373884ca6d85ef9
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
version: bump minor version number

Changes:
  - external headers have been merged into a single file
  - the external API has been cleaned up
    - there are now separate decoders for different layers
    - the encoder now takes a struct pt_packet
  - documentation has been extended
  - all documentation has been moved into doc/
  - we now use doxygen to document the external API
  - fixed a bug where events were attributed to the wrong loop iteration
  - fixed a few instruction decoding bugs
  - fixed bugs that broke the release build
  - ptdump:
    - error reporting has been aligned with ptxed
    - new options:
      --cpu      set cpu for decoding
      --quiet    suppress normal output
      --no-pad   suppress PAD packets
      --no-sync  suppress the initial sync
  - ptxed:
    - we now use XED from PIN 2.13-62732
    - option changes:
      --pt now accepts an optional range
    - new options:
      --cpu      set cpu for decoding
      --verbose  print information about the process image
  - pttc:
    - new options:
      --cpu      set cpu for decoding
  - test.bash:
    - now accepts cpu specifiers in .ptt files
    - now indicates any kind of error in its return value
    - new options:
      --cpu      set cpu for decoding

Change-Id: Ice967f8857e6d869bfc2a09f2aa92789d2fdd7a6
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>