Update log.c

Issue 348 dstt vs src
Merge pull request #350 from jrossi/issue-348

Update log.c
display defaults for PREFIX and MAXAGENTS in make help
fix several -Wextra warnings
Merge pull request #351 from cgzones/defaults

display defaults for PREFIX and MAXAGENTS in make help
fix compilation color
Merge pull request #353 from cgzones/reenable_colors

fix compilation color
Merge pull request #352 from cgzones/wextra

fix several -Wextra warnings