norma-dmm: Added separate driver siemens-b102x for Siemens B1024-B1028 DMMs (just for cosmetic reasons).
norma-dmm: Added request timeout mechanism; docs.
add explicit configure flags for ftdi/serial/usb libraries

This makes it a lot easier for distros to control this functionality.
asix-sigma: fix build time warnings

We need to include unistd.h for usleep():
hardware/asix-sigma/asix-sigma.c: In function 'sigma_fpga_init_bitbang':
hardware/asix-sigma/asix-sigma.c:450:3: warning: implicit declaration of function 'usleep'
   usleep(10000);

And we need to tweak the type of chunks_per_read to match dl_lines_total:
hardware/asix-sigma/asix-sigma.c: In function 'download_capture':
hardware/asix-sigma/asix-sigma.c:1161:39: warning: comparison between signed and unsigned integer expressions
   dl_lines_curr = MIN(chunks_per_read, dl_lines_total);
do not add check to common cflags/libs

Only the unittests use these flags, so don't go linking them in for
the main library too.
detect version 1.x of libftdi library

The FDTI library changed version, module name and also soname, so add an option to detect it
when the 0.x version is not found. The 1.x API is compatible enough for libsigrok to build.
Lower libftdi1 requirement to 1.0 (builds fine too).
README: Document that libftdi1 is also an option.
serial-dmm: Implement request timeout mechanism.

(fixes request flooding for Voltcraft ME-42 and M-3650CR)

This fixes bug #345.
manson-hcs-3xxx: Initial driver skeleton.
manson-hcs-3xxx: Initial driver implementation.

Currently supports only few HCS-3xxx models (tested on HCS-3202), and
not all commands/operations yet.