additional upper pitch limit during launch

The pitch limit can be used by the laucnhdetector to limit pitch during
critical phases of a launch. For example this can be used to limit pitch
while attached to a bungee differently from the standard pitch limit.
Merge remote-tracking branch 'upstream/master' into launchpitchlimit_master
launch pitch limit: add mtecs interface
Merge branch 'launchpitchlimit' into launchpitchlimit_master
FTP: Add req_opcode field for return request opcode in response message.
FTP: Make responses start from opcode 128.
FTP: Remove CRC32 from protocol.

Extra crc not needed because mavlink already has crc16.
FTP: remove reserved uint32 from header.
FTP: Update unit test for new header size.

_list_test failed.
FTP: remove padding zeroing.
Merge pull request #1357 from vooon/ftp_opcode

FTP request opcode
Don't send back U or ./.. entries from List command
Update for not getting back "." entries
Merge pull request #1356 from PX4/launchpitchlimit_master

FW: additional upper pitch limit during launch
Fix List command test

Return order from List command is not repeatable
Merge pull request #1358 from DonLakeFlyer/FTP

Fix mavlink unit test
FTP: Add skip entry information for proper offset calculation.
Merge pull request #1362 from vooon/ftp_list_fix

FTP: Add skip entry information for proper offset calculation.