bugfix: we might miss the linker option -ldl when we shouldn't.

bugfix: we might miss the linker option -ldl when we shouldn't.

bugfix: access nonexistent fields in the "ngx" table in init_by_lua* …

…could lead to the exception "no request object found" because of the overreacting __index metamethod of the "ngx" table.

more coding style fixes.

doc: bumped version to 0.9.15; also stated that we work with nginx 1.…

…7.10.

updated the copyright years.

doc: bumped version to 0.9.13 and also claimed the compatibility with…

… nginx cores up to 1.7.7.

tests: suppressed a warning from the test scaffold for a timer test c…

…ase.

doc: bumped version to 0.9.12.

bumped internal code version to 0.9.12.