some fixes for TDD

• add configuration parameter end_of_burst_delay
• add configuration parameter sf_extension
• some fixes

To use the parameters, add variables end_of_burst_delay and sf_extension in the configuration file.

For example:

RUs = ( 
    {   
       local_rf       = "yes"
         nb_tx          = 1
         nb_rx          = 1 
         att_tx         = 20
         att_rx         = 0;
         bands          = [7];
         max_pdschReferenceSignalPower = -27;
         max_rxgain                    = 105;
         eNB_instances  = [0];
         sf_extension = 312;
         end_of_burst_delay = 200;
    }   
);  

See commits 275e5b3a and ee5b7390 for more details.