patterns/includes: Update standard library and patterns to support the new bitfields (#102)

* Add `current_bit_offset()` and `read_bits(...)` to `std::mem`

* Replace deprecated BitfieldOrder enum values with new clearer names

This adds new options named `MostToLeastSignificant` and `LeastToMostSignificant` to replace the old `LeftToRight` and `RightToLeft` names. These names should be much clearer about what they affect and how.

* Throw errors when `std::core::(get|set)_bitfield_order()` are called

* Update all patterns to work with the new bitfield behaviors

patterns/ip.hexpat

@@ -1,5 +1,4 @@
  #pragma endian big
- #pragma bitfield_order left_to_right
 
 #include <std/sys.pat>
 #include <std/io.pat>