#151182 - [65cat] Local history is cleaned every start up

Problem:
caused by an integer overflow. Two different scenarios if given value  
 > 24:
a) the computed value is invalid (< 0) - the whole LH storage is  
cleaned on startup
b) the computed value is wrong (value between 1 .. 24) - the files in  
the storage are removed earlier as they should

fix:
1.) simply cast the value
2.) properly check the "time to live" field in the options page

http://www.netbeans.org/issues/show_bug.cgi?id=151182
http://hg.netbeans.org/main/rev/e2a3cb674f22

thanks