Remove the human component from builds

[NotCompsky]

Replace wget -O 3rdparty/include/libb64.h https://.../libb64.h && wget -O 3rdparty/src/base64.c https://.../cencode.c with wget -o 3rdparty/include [urls]. Involves changing base64.c to cencode.c in some files.

Create a cross-platform FindMySQL.cmake (that finds MariaDB too) to remove need to specify paths/etc for most people.