feature: Init - Add Init code
1. Add initial code section
2. Add FD_GenerateAGCTrainingSymbol.m for training symbol generate

Signed-off-by: Tim Huang <artines1@gmail.com>
feature: Init - Add function for generate channel estimation symbol
1. Add function FD_GenerateWideCETrainingSignal.m
2. Implement training symbols

Signed-off-by: Tim Huang <artines1@gmail.com>
Merge branch 'feature_init' into develop