Use monotonic clock to prevent timing issues

This patch replaces the gettimeofday()/timeval-system with
uses of clock_gettime() with a monolithic clock and timespec-structs.
gettimeofday() is not accurate and prone to jumps and POSIX.1-2008
marks it as obsolete. Read more here [0].

The patch should speak for itself and decreases the binary
size for me by almost 200K(!).

[0]: http://blog.habets.pp.se/2010/09/gettimeofday-should-never-be-used-to-measure-time

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
Fixed wrong nanosecond factor 10E6.

Commit 5edeec1 introduced a wrong factor for nanosecond computation, the correct
value is 1E6. Time and timeout values are 10 times less than they should be and
this cause high CPU usage.

Reported by pyroh on IRC. Thanks!

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
Remove CEIL macro

This macro was not correct in some cases, and it was used only in
one place, where we did'nt get any benefit in performance of in size,
so the macro is removed and ceilf is used instead of it. The only
function needed from math.h is ceilf, so this patch defines the
prototype of it instead of including math.h.
added .gitignore file
symlinked config.def.h to config.h
initial commit of my config.def.h
default font is now DejaVu Sans Mono for Powerline