Added specifying ordinal hash tag positions

if the start hash tag character is the same as the end hash tag character, only the first hash tag will be used

    hash_tag: __
    1_2_3_4 -> 2

Applying ordinal hash tag positions, you can get the nth hash tag if multiple hash tags exist, reverts to whole key if nth hash tag is not found

    hash_tag: __
    hash_tag_pos: 2
    1_2_3_4 -> 3

    hash_tag:__
    hash_tag_pos: 2
    1_2_3 -> 1_2_3