Make struct argparser opaque (& private) to reduce exposure of private structs

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Reduce exposure of dict's private data structures

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Cleanup & reduce list's exposed surface

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Cleanup queue's visible API & structures

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Final removals of globaly visible data structures (pool & slab)

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Make slab.h & pool.h private

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Add a rudimentary check for the existence of pthreads

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>