Modified FSharpMemberFunctionOrValue to include an Overloads property.

This property returns all the overloads of the current MethodInfos
defined apart from the defining MethodInfo from
FSharpMemberFunctionOrValue.

e.g for DateTime.Now.ToString() would have a symbol of
FSharpMemberFunctionOrValue with an initial signature defined of:
 unit -> string

with Overloads of
IFormatProvider -> string
string -> string
string * IFormatProvider -> string
Add method GetDeclarationSymbols to CheckFileResults/TypeCheckInfo

This allows FSharpSymbols to be returned from the current location
rather than a textual DeclarationSet.  This means that each symbol can
be queried and interpreted by the editor as it sees fit.
Added xmldoc summary
Apply the same filtering as used by GetDeclarationSymbols

We might want to change this in the future to allow retrieval of only
certain symbol types at a declaration point, so Ive chased not to
refactor the common filtering in ServiceDeclarations.  We want to
provide an option to show operators for instance etc.
Added tests for GetDeclarationSymbols

These tests are the symbol version of the GetDeclarations tests.
Merge pull request #182 from 7sharp9/getDeclSymbols

Add method GetDeclarationSymbols method to CheckFileResults/TypeCheckInfo