2.1.0

Release with the latest upstream changes.

ILSpy with StringConcatToAddition

Added StringConcatToAddition AST transformation which transforms "String.Concat(a, b, c, d, ...)" into "a + b + c + d + ..."

ILSpy with FlattenElseIf

This contains FlattenElseIf which transforms most "else { if }" into "else if { }".
Also ILSpy's StackReserve was increased to allow decompiling a large number of if statements.