Implemented LowercaseLongLiteralSuffixIssue.
Merge branch 'master' of git://github.com/icsharpcode/NRefactory into luiscubal-confusing-literal-suffix
LowercaseLongLiteralSuffixIssue: Only check long/ulong literals. Check if literal ends with 'l' or 'l*', instead of searching the whole literal string.
LowercaseLongLiteralSuffixIssue: Disabled for 3ul (the 'u' in the middle of the literal makes it hard to mistake 'l' by '1')
3lu is now replaced by 3LU instead of 3Lu.
Modified tests to show the new behavior.
Merge pull request #253 from mono-soc-2013/luiscubal-confusing-literal-suffix

Confusing literal suffix 'l' for longs