Added the still experimental ExtendableMessage trait. Version bump.
Merge remote-tracking branch 'origin/master'
fix error cases for -I and --proto_path

if you use "-I(folder that doesn't exist yet)", scalabuff will exit silently. this fixes the missing "else" to make it print a warning and continue. i also fixed the same bug in --proto_path while i was in there.
Merge pull request #48 from robey/patch-1

fix error cases for -I and --proto_path