client/engine: MOVE_UP/DOWN fix

- Pressing the MOVE_UP/DOWN keys would adjust the vertical movement. This
  caused the viewer to move forwards/backwards if the camera was pointed
  at a steep upwards or downwards angle. Behavior should be that the
  camera moves distinctly upwards or downwards, regardless of horizontal
  motion.

Signed-off-by: Paul Holden <paulholden2@gmail.com>
client/engine: stderr message on log open fail

Signed-off-by: Paul Holden <paulholden2@gmail.com>
client/engine: Print chk_sysreq error to log

Signed-off-by: Paul Holden <paulholden2@gmail.com>
client/engine: Ambiguous field 'state'->'initmask'

- Used to keep track of what libraries have been successfully initialized
  so that engine_deinit() knows what to do.

Signed-off-by: Paul Holden <paulholden2@gmail.com>
client/engine: Fix OpenGL version check

Signed-off-by: Paul Holden <paulholden2@gmail.com>
Merge branch 'client-fixes'

Signed-off-by: Paul Holden <paulholden2@gmail.com>