Project structure is currently as follows:

src/include/
  -- installed headers for public APIs

src/util/
  -- common utility functions (currency representation,
     Taler-specific cryptography, Taler-specific json
     support)

src/pq/
  -- Postgres-specific utility functions

src/mint/
  -- taler mint server and helper binaries

src/lib/
  -- libtalermint: C API to issue HTTP requests to mint, including testcases