integrate rrd_snprintf
include snprintf.m4 in the distro
fix preprocessor warnings
Added locale independent versions of strtod function
Removed setlocale calls, used rrd_strtod & rrd_snprintf
Fixed some terrible indentations
Merge pull request #513 from Sweet-kid/rrd_snprintf

Removed setlocale instances https://github.com/oetiker/rrdtool-1.x/issues/504 #510