SubOrderFormativeElements() and histosols

[dylanbeaudette]

The current strategy breaks down with "fibristels" "folistels" "hemistels" "glacistels" "sapristels", due to the contraction of "hist" to "ist".

Some ideas:

• custom look-up for these taxa
• use the strategy employed by SubGroupFormativeElements() where matching is performed on the formative elements vs. exact matching of parent taxa

[brownag]

This issue is resolved since the use of the lookup table using letter codes to denote parent-child relationships with little-to-no pattern matching required. Came with reorganization of the package in #14