Restructure code.

   This is quite a bit in one commit but it:

       * Splits the app into an app and module so the analysis components
         can be re-used. Also tidied up all the header files in the app.
       * Updates the app_handler to syphon off i2s samples (renamed to i2s_tap)
       * Changes the communication between the i2s tap and the analyzer
         slightly
       * Updates to be able to test based on i2s loopback

   Currently the code only works in simulation (axe command line added to
   Makefile)
Merge branch 'master' into d
Update spectral analysis
Update app to run on XR-USB-2.0-MC board.
Add multiple channel support.
Add more advanced sinewave generation.
Update freqency detection resolution
Tidy up a bit
Make glitch detection relative to amplitude
Add multiple configs
Tidy code up a bit
Fix xscope/simulator config
Add lost signal detection to analyzer
Add more debug output
Move signal generation into module
Rename app
Add eclipse metainfo