Merge pull request #61 from susji/walkdir_harder

library: Adhere better to WalkDir's behavior

Merge pull request #60 from susji/tolerant_walk_errors

library: A single error is no cause to give up

Merge pull request #57 from susji/better_ini_errors

First round of changes for better handling of configuration files. Next we
need to provide the user a cleaner view of config errors without resorting
to `-debugfile`.

Merge pull request #55 from susji/build_with_tag

Makefile: Use tagged version if such exists