main: Use '1000000' instead of '1e6' to avoid FPEs

The static value loaded when '1e6' is requested is a double, which means
that during the multiplication in line 70 GCC generates floating point
operations. These can cause floating point exceptions during thread
context switching and can be avoided by explicitly requesting '1000000'.
Makefile: Generate debug flags
Merge branch 'master' of github.com:jpfender/riot-gossip