Georgr/merge candidate

[da-gazzi]

Features added:

• add support for mixed-hw conv1d
• add support for multiple inputs (only with GAP8_board_L2)
  • use n_inputs key in network description .json (e.g., "n_inputs": 4)
  • input file name of input n: input_n.txt
  • intermediate result file name of input n for layer l: out_n_layerl.txt
  • default is n_inputs=1; in case of n_inputs=1, file names are as before (input.txt and out_layerl.txt)
• add support for signed inputs
  • use boolean input_signed key in network description .json
• add support for <8b inputs
  • use input_bits key in network description .json

[da-gazzi]

I failed at git, sorry (feel free to delete this and the previous PR)