Add an icon png file of 64x64 pixels.

  Closes #57, or so I think.
Handle SDL inactivity notifications to suspend the game (ie no drawing, no sound)

  Suspending sound does not work with libopensl-software.
  Not sure how to proceed from there...
Clear all gcc's warning. Had to clean the code slightly.

  Closes #53
Replace ingame keys setup by a user editable configuration file.

  Ingame setup of keys was not satisfactory for several reasons:
  - all keys should be set in order, no way to change just a few
  - the font was barely readable
  - no way to setup a different control mode than keyboard
  Plus we like text files so much more!

  So now to change the default key mapping you have to create/edit
  .fachodarc in your homedir (or current dir). Fachoda will read it
  but not write it.

  Also included: a tool to get the SDL name of any key: getkeyname.

  Closes #39.
Install .fachodarc in DOCDIR
Fix a bug when a key is released just after pressed

  Now we keep another bit per key, meaning 'this was pressed since last check'.
Pause do not any more prevent drawing.

  So that HUD messages such as "PAUSED" or quit prompt can be shown.

  Closes #54

  This makes more important to distinguish between thrust and throttle,
  though, since for now the delay between pushing the motor power and
  thrust is only due to the time it takes to increase throttle by small
  increment. But now we can put throttle to 100% while in pause...
Provide explicit rule for building getkeyname from getkeyname.o

  Since default GNU make implicit build rule write LDFLAGS before the
  object name, so some build chain fails to include some SDL functions.
  We probably should not use LDFLAGS for -lname options but LDLIBS.

  Closes #59
Fix same bit keys shared for several keys

  Closes #39
Maemo5: default .fachodarc for N900