start with l2cap implementation

removed accidental copyright note

implement power control by client (only single user mode yet) with hci_set_power_mode command

extract l2cap signaling code into l2cap_signaling

extract utility functions into utils.c

extract code for HCI Command packet construction into hci_cmds.c

forgot to add, but nobody complained

renamed socket_server to socket_connection. it will be used by both client and server

fix l2cap signal packet generation - connection to BT HID working now

fixing bugs created while copy \& paste of code without event a single test. example connects, does paring and gets stuck in l2cap statemachine

minimal test code (same as in main.c earlier but now as btstack client app) - ipc not working yet