issues from today's review of the real-time system

[MichaelCoulter]

• rename simulator_process something like datasource_process and move out of simulator folder
• rename main_process supervisor_process
• create a buffer in the decoder to retain dropped spikes from the previous 2-3 bins
• check calculation of prob_no_spike in decoder_process
• create a record with the time bin for each decoded spike
• move stim_decider from main_process to decoder_process
• send shortcut message from stim_decider
• send ripple threshold message to encoder and decoder nodes
• update any uses of convolve function with the solution we decide to implement in the offline code