Moved one line shit out of core.cpp

inlined core::isRunning() and const corrected it.
More inlining
Changed regarding Torrent::getEta()

Replaced arbitrary 817 return value with -1 and added a case to
getTimeString( boost::int64_t ) to handle negative values.
Merge pull request #118 from AndrewBerry/master

inlined core::isRunning() and const corrected it.