Aubit 4GL SVN-Code

The runtime was split across two trees: four files under lib/liblex/lex_cs/
runtime and the other thirty-seven under dotnet/src/Aubit4GL.Runtime, joined by
a relative <Compile Include> reaching out of the project. One assembly, one
partial class, two places to look - and the cross-tree include was also why
building outside the fidelity harness kept failing to resolve the project
reference through a symlinked tree.

The four move to where the rest of them are: FglStrings, FglEnvironment and
FglProcess are Fgl builtins so they join the others in Types/, and
FglModuleBuiltins extends FglModule so it sits beside FglSession. The include
is gone and the emptied directory with it.

No code change - the files move as they are, with their history.