Fix ruserdialog.h included as system header

[amaa-99]

Corrected <ruserdialog.h> to "ruserdialog.h".
(closes amaa-99#127)

[amaa-99]

@mvo5 With the migration to Meson I'm no longer able to open the project on the IDEs that I'm using.
I'll be a bit limited on development until I find some workarounds to get things working again...

[mvo5]

@mvo5 With the migration to Meson I'm no longer able to open the project on the IDEs that I'm using. I'll be a bit limited on development until I find some workarounds to get things working again...

Oh, I'm really sorry to hear that - what IDE is that? I absolutely want to unblock you here.

[amaa-99]

@mvo5 On Linux it tend to use Eclipse in general (it matches what's used on most commercial projects I work on) and QT Creator (good usability). The meson support plugins seem to have been abandoned...
When I can, I throw parts of the code into (full) Visual Studio (on Windows) - the code analysis and refactoring tools are quite good there.
VS code seems to understand Meson well enough, but I don't find it practical as an IDE (decent editor for AI generated code, for those who find that useful).