Remove use of PKG_CHECK_VAR introduced in 4b0861ae.  Closes: #271.
scrobbler2: improvements to the configuration migration procedure (Feature #263).

Scrobbler2 will be enabled if the old scrobbler was enabled.
Only migrate the settings once, and only if the old scrobbler was configured.
scrobbler2: Inverted logic on the check for migrated preferences.
search-tool: Always return MAX_RESULTS if >= MAX_RESULTS are found.
Update translations from Transifex. 4 new languages: Greek, Finnish, Indonesian, Kirgyz.
amidi-plug: Fix cppcheck warnings
sndio: Fix buffer overflow due to using strlcpy().  Closes: #277.
adplug: Minimal fixes for warnings with GCC 4.8.
console: Fix use of uninitialized values if fread() fails.
Remove trailing whitespace.
Remove sidplay1 support.
sid: Remove support for incompatible sidplay2 variants.
sid: ReSID is the only supported builder.
sid: Port to sidplayfp. Closes: #173.
sid: Remove some cruft.
sid: Audio is always 16-bit in sidplayfp. Remove sampling rate conversions since we can do this elsewhere.
sid: Get rid of "template" header.
sid: Remove a bunch more cruft. sidplayfp is now hard-coded.
Customized m4 macros for sid are no longer needed.
sid: Cleanup.