CERE v0.2.0 release

• Fixed autotools installation: now CERE can and must be installed
  with make install. All libraries were renamed with a common libcere_
  prefix. (#6)
• ccc is now called cerec (cere compiler)
• Fixed the documentation and renamed some configuration variables.
  To set the replay repetitions now one should use CERE_REPLAY_REPETITIONS.
  To choose the warmup mode one can configure CERE_WARMUP.
• Fixed a capture/replay bug that could happen when global static variables
  were optimized during capture but not replay. (#51)
• Cere flags now accepts a file of flags combinations (#24)
• Removed the undocumented and unused dump-all mode.
• Fixed an issue with the report generation coverage plot.
• Fixed various bugs in cere python driver.
• Added various missing tests.