ColumNameCache concurrency fix

NH-3420  bug fix
Formatting
Merge branch '3.1.0GA_column-cache-concurency-fix' of git://github.com/grzpas/nhibernate-core into grzpas-3.1.0GA_column-cache-concurency-fix
Really fix formatting.
ColumnNameCache.cs: Can't think of a reason to store nullable ints in the cache dictionary, since we never store the value null - and for retrieval we can use the return value of TryGetValue().
Resharper settings: specifically use spaces for alignment, since tabs are used for indentation. (This is resharper default and recommended anyway).
Fix NH-3420: Merge branch 'grzpas-3.1.0GA_column-cache-concurency-fix'