opencl: move lookup-gap check for kernel zuikkis to after it is set from opt_lg.

Introduced by https://github.com/veox/sgminer/commit/89d641628b79f03b0520f0eb2586275a23420a0f

Closes https://github.com/veox/sgminer/issues/172
config: write `algorithm` to config if not default.

Closes https://github.com/veox/sgminer/issues/175
core: remove total_users, total_passes, total_userpasses (no longer used).

Silence gcc warnings.

Need for these accounting vars removed a few commits ago by troky.
adl/misc: mention that the found adapters are logical.
adl/misc: remove unused iNumDisplays.

Silence gcc warning.

Added in a7bca5663390e59b36cc2c14692df124ac6c954f by Joe4782, but
never used.
core: silence gcc warning about sprintf() use in add_pool() - this time for sure.
adl/misc: remove unused lpAdlDisplayInfo (silence GCC warning).
doc: minor README wording.
doc: update README.md with links to mailing lists.
Revert "fix for mingw-w64"

This reverts commit 32b13ccb46eb2607c5fd40052318fcdbd8d32dca.

Reported by Wolf0 (aka wolf9466) to not break MinGW 64-bit compilation
with GCC 4.8.2 (latest stable).
misc: update NEWS.md with reference to mailing lists and duplicate entry removal.
add support for setting algorithm/nfactor for each pool separately, and fix bugged OpenCL thread cleanup (thread shutdown)
Change algorithm more robustly and faster, previous way was buggy
added clarification for dependencies

Improved clarity of dependencies by adding example of how to install dependencies using apt-get. It was not clear whether `autoreconf -i` would install the dependencies or not. And how to install the dependencies if a user doesn't know how.
made debian apt-get a one-liner
Merge pull request #181 from morenoh149/patch-1

added clarification for dependencies
log: do not show pool difficulty changes on non-current pool.

Keep log spam down when using a lot of vardiff pools, or if a p2pool is
a fallback.
misc: don't violate reserved identifier naming convention.

Closes https://github.com/veox/sgminer/issues/177
config: rename --pool-priority to --priority, --coin to --description.

There are now get_current_pool() and current_pool(), which is confusing.
Moved them closer together, so it's at least obvious.
misc: Bump version to 4.1.242.