move everything to subfolder theories/

theories/algebra/sts.v

theories/algebra/updates.v

theories/base_logic/base_logic.v

theories/base_logic/big_op.v

theories/base_logic/deprecated.v

theories/base_logic/derived.v

theories/base_logic/double_negation.v

theories/base_logic/hlist.v

theories/base_logic/lib/auth.v

theories/base_logic/lib/boxes.v

theories/base_logic/lib/cancelable_invariants.v

theories/base_logic/lib/counter_examples.v

theories/base_logic/lib/fancy_updates.v

theories/base_logic/lib/fractional.v

theories/base_logic/lib/invariants.v

theories/base_logic/lib/iprop.v

theories/base_logic/lib/na_invariants.v

theories/base_logic/lib/namespaces.v

theories/base_logic/lib/own.v

theories/base_logic/lib/saved_prop.v