Fix compilation errors

See merge request !3

Tests: changes following factorization of logs options into bc_tester

See merge request !1

Fix/rpm install libdir

See merge request !2

Add a mutex on database access
API with direct cache access is deprecated

+fix memory leaks in tests

gcc was right to complain!

+ improve code readability

Retrocompatibility ensured by build option which is on by default for now.

- this function shall be used in a mono-device per account environment
- give the trust status of a peer uri based on the
last device involved in a ZRTP exchange associated to that uri.

+ do not store in cache any peer information until first negotiation succeeds

- better trace
- fix bug in ECDH specifics tests

Do not append project build version to package name if it is 0 (that's the case for tagged releases).

Not defined in ZRTP RFC.
Bzrtp uses curves 25519 and 448 following the RFC7748(little endian or public values)
If zrtpcpp uses big endian(likely), we must choose an other 4 chars code for our algo