Fixed typo
Fixed comments of avl_del function interface
Updated function interface description of avl_find
Removed ternary operator due in avl_height()
Removed ternary operator in avl_node_cnt()
Added a test for checking for duplicates
Added more description to comment of ht_destroy()
Added config parameter to ht_destroy()

Didn't change the implementation itself. Just added the parameter.
Added more information to comment for ht_find()
Added information for ht_del() documentation
Changed return value of ht_del() (interface)
Added comment to dbg macro
Removed obsolete notes of MAX and MIN macro
Merge pull request #130 from TheNeikos/add-ll_test

Added a test for checking for duplicates in linked list
Merge pull request #129 from manuelmessner/fix-avl_header

Fix avl header
Merge pull request #132 from manuelmessner/fix-util_headers

Fix util headers
Merge pull request #131 from manuelmessner/fix-ht_header

Fix ht header