Updates for C# and SQL users.  Everyone else is fine skipping this one.

The C# parser had fallen out of date, so I went through the language specifications and updated it to support all the changes through C# 9.0.  That means Natural Docs can properly handle:

• Records, including automatically generating properties for parameterized ones like "record MyRecord (int X, int Y);"

• Tuples

• Init setters in properties

• Expression-bodied constructors, finalizers, and conversion operators.  It was already supported for functions, properties, and other operators.

• Function pointers

• Newer keywords and modifiers

• Syntax highlighting for interpolated strings and constants with digit separators

Plus other smaller things.  Most of these features already worked fine if they appeared in a function body but might have thrown things off if they appeared in a prototype.  Now they'll work everywhere.

I fixed a couple of bugs in the SQL parser as well.  Next up are a couple of small features which aren't very exciting but are needed to lay the groundwork for SystemVerilog.