Introduced the Fields query class,

which enables query of static fields.
Added a Null Guard Clause.
Checked expression to see if it was a proper

member expression.
Checked that the selected member is a field.
Added rudimentary XML comments on Fields class.
Maded Fields class static,

because it had no instance state anyway.
Incremnted minor version,

in order to indicate that the addition of non-generic static Fields class
for strongly-typed queries of static fields constitutes a new feature.
This resolves #77 (https://github.com/ploeh/Albedo/issues/77).