Version 0.0.49

* Fixed critical bug in filesystem watchers; file:impress.js;
function:watchCache
* Added timers array for watchers to minimize cache rebuilding when same
file changes multiple times within small interval (2 sec)
* Added clearCacheStartsWith into impress.js, improved and optimized
* Fixed Impress server shutdown and restart; memory leak prevented;
file:impress.js; method:impress.stop