Fix file importing code to not generate some duplicate directories

build_file_tree() depends on the fact that the contents of a directory
are sorted immediately after it in the file list, but '.' sorts before '/'
lexicographically, so you'd actually end up with, eg:

/etc/yum
/etc/yum.conf
/etc/yum/pluginconf.d

which would cause a second entry for /etc/yum to be added to the file
list.

For now I've fixed this by make compare_filenames() do a special strcmp
by hand, manually sorting '/' before anything else.

redo test framework, with tests taken from yum sources

(none of them pass yet...)

misc fixes for edge cases

1) sets with only one package
2) packages with only one property
3) sets with only one property

remove some unused code

(trivial optimization)

add a missing comparison to ensure correct repo sorting

Split razor_package and razor_entry names into name and flags

split razor_property.name into name, flags, and type bitfields

Change list flags back to 8 bits instead of just 2

improve the list abstraction with "struct list_head" and "struct list"

both structs are actually just uint32_t's in disguise, using bitfields
to avoid the need for explicit bit operations, and using two type names
to hide the RAZOR_IMMEDIATE hack from the public API