Mega-commit to document the API with doxygen.

Some changes were made to the API when making the documentation:

- A few exported functions are now hidden, because they were only used
  internally in the library.
- A few exported symbols were renamed to document them better than
  previously.
- Cosmetic changes all along the way, as well as some fixes here and there.

--HG--
extra : convert_revision : xtraeme%40gmail.com-20100121021019-onbsivlrhdb7t3ou

bin/xbps-bin/show-deps.c

@@ -42,7 +42,7 @@ xbps_show_pkg_deps(const char *pkgname)
 
 	assert(pkgname != NULL);
 
-	pkgd = xbps_find_pkg_installed_from_plist(pkgname);
+	pkgd = xbps_find_pkg_dict_installed(pkgname, false);
 	if (pkgd == NULL) {
 		printf("Package %s is not installed.\n", pkgname);
 		return 0;
@@ -79,7 +79,7 @@ xbps_show_pkg_reverse_deps(const char *pkgname)
 	prop_dictionary_t pkgd;
 	int rv = 0;
 
-	pkgd = xbps_find_pkg_installed_from_plist(pkgname);
+	pkgd = xbps_find_pkg_dict_installed(pkgname, false);
 	if (pkgd == NULL) {
 		printf("Package %s is not installed.\n", pkgname);
 		return 0;