serial: re-implement sr_serial_find_usb() using new libsp APIs
build: Require libserialport version 0.2.0.
rigol-ds: Fix duplicated vendor string for Agilent devices.
hameg-hmo / rigol-ds: Restore compatibility with std_dev_clear()
added pipistrello-ols

Conflicts:
	configure.ac
	src/hwdriver.c
fixed a problem with USB defines
fixed typos
added edge triggers
DEMUX and RLE fixes
pipistrello-ols: Preliminary port to current API.
pipistrello-ols: Disable unused trigger stages.

Thanks to Magnus Karlsson for this fix.
Avoid warnings on all-zero static struct entries.
fx2lafw: Code cleanup.
input: s/format/module in all naming.
input: make sr_input{_module} opaque to clients.
input: Introduce new input module API.

This is a work in progress.
input: Fix up API documentation.
input: Fixes and VCD.
input: Frontends don't need to see SR_INPUT_META_*.
input: Actually return a NULL-terminated array.