Dialogs are not imported by default

[whitebyte]

import dlangui;

// without this two lines Dialog and FileDialog are undefined identifiers, but other widgets works just fine
// import dlangui.dialogs.dialog;
// import dlangui.dialogs.filedlg;

...

FileDialog dlg = new FileDialog(caption, window, null); // error if two dialogs are not imported explicitly

[GrimMaple]

I think I'm against public imports, but feel free to submit a PR, I'll merge it

[whitebyte]

I don't think I'm opening a PR against maintainer's will. I don't have a strong opinion on public imports, what actually bothers me here is http://buggins.github.io/dlangui/ddox/dlangui.html
Some things are imported by default while others are not, and it's not clear what exatly import dlangui imports. "most useful DLANGUI modules" is pretty vague