Various drivers: Drop some unneeded lines.
demo: Fix typos.
la8: Cleanups, cosmetics, simplifications.

Also, make some LA8 references more generic in preparation of
LA16 support.
la8: Add support for the ChronoVu LA16.

The ChronoVu LA16 is a new logic analyzer from ChronoVu with some
differences in features compared to the LA8, e.g.

 - Supports 16 channels (instead of 8).
 - Max. 200MHz samplerate (instead of 100MHz).
 - Supports state triggering (low and high channel value) and edge triggering
   (rising or falling edge), the LA8 only supports state triggering.

This driver now supports both the LA8 and LA16, but it needed a few
changes:

 - Add support for detecting multiple device instances at all.
 - Add support for both LA8 and/or LA16 devices being detected.
 - Add a device profile struct for LA8-/LA16-specific device properties.
 - Move the samplerates list to devc (it's different for LA8 and LA16).
 - Split scan() into two functions, one for scanning, one for adding a device.
 - Expand some variables and fields from uint8_t to uint16_t in order to
   support 16 channels.
 - Update the samplerate related functions to support the LA16's 200MHz.
 - Various other minor updates in order to better handle both device types.
 - Various error handling improvements and simplifications.
 - Also, replace time() with g_get_monotonic_time() everywhere.

This also fixes bug #247 (which was related to incorrect handling of
resources during scan and open of the device, which was exposed by
PulseView allowing multiple consecutive scan/close/open calls).
Rename 'chronovu-la8' driver to 'chronovu-la'.

The driver now also supports the LA16 device (and possibly others in the
future).
chronovu-la: Document that streaming is not possible.

This closes bug #261.
chronovu-la: Fix byte order for LA16 samples sent to the bus.
chronovu-la: LA16 has fewer max. samples than LA8.

Each LA16 sample is 16bits wide (LA8 samples are 8 bits wide). Adapt the
number returned for SR_CONF_LIMIT_SAMPLES in config_list() accordingly.
Various drivers: Expose SR_CONF_TRIGGER_TYPE.

Without this, sigrok-cli --show (for example) will not show the
supported trigger types.
fx2lafw: fix possible use of uninitialized variable (gcc-4.9 warning fix)

hardware/fx2lafw/protocol.c: In function 'fx2lafw_command_start_acquisition':
hardware/fx2lafw/protocol.c:113:7: warning: 'cmd.flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
   (cmd.flags & CMD_START_FLAGS_CLK_48MHZ) ? "48" : "30");
       ^
scpi_usbtmc_libusb: disable bulk_out clear_halt for Rigol DS1000

fix hangup issue with Rigol firmware version 00.02.02.02.00
scpi_usbtmc_libusb: disable all clear_halt for Rigol DS1000
rigol-ds: fix long memory depth setting on DS1000
configure.ac: Clearly mark required and optional libs.
chronovu-la: Show errors other than "device not found".

This can be useful for the user to see, e.g. for permission related
issues (device is there, but cannot be accessed).
sr_dev_inst_new(): Use NULL (not "") if version unknown/nonexisting.

Unify the whole code-base to use NULL there, not a mix of "" and NULL.
.gitignore: Add test-suite.log.
python: Add lost functionality expected by sigrok-cli-python.
Support passing Python callbacks to sr_session_source_add.