Added dependency duct++; added assertion macro¹.

1: Replaced assert() with always-enabled MURK_ASSERT().
Added serialization routines; see full commit message.

serialize:
    added compound serialization routines.

Desc:
    added tie data accessors and mutators¹.

test/common/common:
    added serialization testing routines.

test/desc/desc:
    moved compounds to common;
    added serialization tests.

1: I am just as terrified as you are. (For science!)
Added tie reset routines.

Desc: added reset_tie().

compound: added compound_reset().

test/desc/desc: reset ties after (de)serializing.