udev rules file: Drop URLs and lsusb.

The URLs to vendor webpages and the full lsusb are in the wiki
already, no need to duplicate them here.
udev rules file: Only list supported devices.

The udev rules file should only list devices that are actually supported
by a driver in the current libsigrok version. Thus, drop all entries for
devices which will get support later on (at which point the respective udev
rule will be re-added again).

Also, add a few missing entries.
Various cosmetics, whitespace, consistency fixes.
ols: Workaround for mac os X stray events
uni-t-dmm: Drop DMM table (comment).

This info is in the wiki already, no need to duplicate in the code.
Drop nexus-osciprime skeleton for now.

This is mostly just a skeleton driver framework at the moment, we'll
bring it back when the driver is fully implemented.
Disable mso-19 per default, mark experimental.

This driver is not yet in a really usable or working state, it'll be
re-enabled by default when we're sure it works properly.
.gitignore: Add some files from the testsuite.
kecheng-kc-330b: Don't build if libusb-1.0 was not found.
ikalogic-scanaplus: Don't build if libftdi was not found.
uni-t-dmm: Fix UT61E bug related to the UNI-T UD-D04 cable.

This fixes bug #136.
alsa: Fix double-free issue.

This fixes bug #129.
Fix sr_si_string_u64() test cases.

The function shall format 1004 as 1.004 k, 1004000 as 1.004 M and
1004000000 as 1.004 G.

References #73.
Format decimals correctly in sr_si_string_u64()

The function previously formatted 1004 as 1.4 k and 1004000 as 1.4 M.
The function now formats 1004 as 1.004 k, 1004000 as 1.004 M and
1004000000 as 1.004 G.

Fixes #73.
unittests: Comment out a testcase.

The boundary test-case with SR_GHZ(18446744073ULL) currently fails, but
that is not practically relevant so comment it out for now, until we add
a proper fix.
Cosmetics, typos.
Consistent use of "IKALOGIC" spelling.

The company name is written all-caps pretty consistently on the
vendor website and docs, so use that spelling everywhere.
udev rules: Add missing IKALOGIC ScanaPLUS entry.
Make sr_session_iteration() static.

This function is not used outside of session.c at the moment, so make
it static for now.
README.devices: Minor documentation updates.