Add gtags files to .gitignore

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Set clang++ as default compiler. Add -pthread as a linker flag

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add missing operators to mpz, mpq, mpbq. Add pp functions for debugging

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add thread_local test

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add methods to mpz, mpq, mpbq

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Move mpz, mpq and mpbq to numerics directory

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>