Fixed integer power operation ipow()

Now it signals error when the result is too large or non-integer.
Imprecise floating point calculations removed.
8 jobs for master in 4 minutes and 14 seconds (queued for 1 second)
Status Job ID Name Coverage
  Configure
passed #4798
mac
configure:mac

00:00:37

passed #4799
windows
configure:win32

00:00:24

 
  Build
passed #4801
mac
build:mac

00:02:32

passed #4800
windows
build:win32

00:01:51

 
  Dist
passed #4803
mac
dist:mac

00:00:23

passed #4802
windows
dist:win32

00:00:19

 
  Pack
passed #4805
mac
pack:mac

00:00:37

passed #4804
windows
pack:win32

00:00:27