Merge branch 'bee-dep-cleanup-pass1'

* bee-dep-cleanup-pass1:
  bee-dep: rebuild logic now 100% in do_rebuild_cachedb()
  bee-dep: get_cachefilename() added to create cache filename
  bee-dep: search pkg only once in cachedb
  bee-dep: init_cache() cleanup
  bee-dep: fix a minor memory leak
  bee-dep: graph_insert_nodes() return 1 on success and 0 on failure
  bee-dep: new ENV handling
  bee-dep: load_cache() return 1 on success and 0 on failure
  bee-dep: cleanup rebuild: move tmpfile logic to save_cache()
  bee-dep: rebuild: don't lock file which gets renamed in next step
  bee-dep: save_cache(), init_cache() return 1 on success and 0 on failure
  bee-dep: use asprintf in main()
  bee-dep: do not exit in hash_new()
  bee-dep: use regular_file_exists() to check for cachefile
  bee-dep: add regular_file_exists() helper function