Significant MessageBox and Dialog Improvements

[tig]

This PR requires #586

It includes many fixes, mostly focused on improving the look, feel, and usability of Dialog and MessageBox

The following bugs should be closed by this PR:

• Closes Resizing the MessageBox width to accommodate all message text #299 - MessageBox now auto sizes
• Closes MessageBox not drawing well when opened on a small screen. #557 - MessageBoxes on small screens
• Closes MessageBox does not deal with long text well; takes size parameters but they are useless #432 - MessageBox does not deal with long text; width/height params are goofy
• Closes MessageBoxneed to take ustrings #521 - MessageBox should take ustrings (BREAKING CHANGE)
• Closes Dialog should have a 1-char padding around the edges. #35 - Dialog should have 1 char padding around edges
• Closes Dialog should use Computed Layout to layout buttons #570 - Dialog should use computed layout for buttons
• Closes UI Catalog: Add Dialogs Scenario #470 - UI Catalog: Add Dialogs Scenario

In addition we get these new features:

• MessageBox.Query called with width and height == 0 get auto-size behavior. A new constructor is added making this easy to use.
• Multi-line MessageBoxes are now supported. Just use \n to add lines. The height of the MessageBox will adjust automatically.
• The MessageBoxes Scenario in UI Catalog provides a full demo/test-case.
• Dialog called with width and height == 0 are sized to 85% container. A new constructor is added making this easy to use.
• Dialog (and MessageBox Buttons are now dynamically laid out using Computed layout.
• A Dialogs Scenario has been added to UI Catalog making it easy to test the API.
• Button now supports BOTH specifying a hotkey with '' and the old behavior of using the first uppercase char (if '' is not found).
• All UI Catalog scenarios that use Dialog or MessageBox now use the simplified API.
• Terminal.Gui.dll now has version metadata and UI Catalog's about box displays it as a test case.
• Button, Dialog, and MessageBox API documentation has been updated/revised.
• View, Window, FrameView, and Dialog have been upgraded to use the new ConsoleDriver.DrawFrameWindow API directly.

[tig]

This has to go in as part of my other big PR. @migueldeicaza : Please comment.

[migueldeicaza]

I am in awe at this work Charlie - thank you so much for this contribution.

I looked at the samples, and it looks like the only breaking change was the incoming parameters for the message box, we could add an API that ignores those parameters?

Did I miss something else?

I think this can go in, given that you have a mondo pull request with too many good enhancements, and we can later add a compatbility layer if someone complains.

[tig]

I am in awe at this work Charlie - thank you so much for this contribution.

I looked at the samples, and it looks like the only breaking change was the incoming parameters for the message box, we could add an API that ignores those parameters?

Did I miss something else?

I think this can go in, given that you have a mondo pull request with too many good enhancements, and we can later add a compatbility layer if someone complains.

Miguel, I'm afraid we are going to need to do a 'breaking changes' release prior to 1.0 if we really want this project to "sing" long-term. There are enough deep bugs due to code churn/atrophy and inconsistencies (such as Frame v Bounds, weirdness around embedded ContentViews, and inconsistencies in how events are defined) that I really think we should bite the bullet and clean some stuff up. This will require breaking existing apps.

IMO, we should do this ONCE.

I think the build we are converging on (which I am calling 0.90) should be that ONCE.

The latest release notes show the breaking changes I've already identified (there may be more, but I've not done any testing to see).

[tig]

That said, I'll ensure the old constructors still work on this one.

[tig]

Now that Miguel's approved, I'm closing this PR as it will be incorporated in mondo #600