Emscripten compatibility and some improvements

[RicoRodriges]

Hi guys. Here some set of updates again.

Game process:

• Level 1 rats start throwing explosive bombs.
• Level 1 soldiers do not have duck projectile attacks anymore.
• There was a little mistake with Level 4 checkpoint positions.
• Fixed an actor's bug with ClampToGround physics. Its tiles were disappeared at the ends of camera rectangle. There was physics and scene position mismatches. Now powder keg and cannons are fixed.
• Also fixed some PID offsets (powder kegs, cannons, rat bombs, ...).
• Improved render process. Invisible background tiles and actors do not render anymore.

Emscripten compatibility:

• Now config.xml file is external by default. It will be downloaded from "working url". But you can embed it by cmake property as usual.
• Remove redundant saves.xml from an emscripten build.
• Canvas can have width and height attributes. The game will be use it on startup.
• Death and teleport fade in/out effects were disappeared. Now fade out effect is fixed. A problem with fade in effect was described in README file.
• The level load menu no longer disappears.

I pumped up html game executor:

• Implemented fullscreen mode!
• Petr I remember you have some problems with screen resolutions. Now you can set canvas width and height before game starting. Or use external config.xml for that (even generate it dynamically).
• Implemented debug panel with console output and cheatcodes. Very useful for mobile devices without keyboard and web developer tools.
• Implemented progress logic to show how much game resources are downloaded.

I don’t know what else the panel may contain :) Now it looks like this:

[pjasicek]

I cannot really express the "wow" I have, thank you so much for the contribution ! I didn't really think anyone would be able to modify much in my codebase :-)

This makes me want to have another final push and finish this project (remaining 4 levels), I may give it a go !

Again, thank you so much for your contributions 👍

[RicoRodriges]

Then I will surprise you that I'm newcomer in game developing (C++ too) and found WebAssembly a month ago :). I'm contributing because I like C++, want to investigate how the games works inside and it's my favorite game. So, debugging and profiling C++ code much better in browser.

I'm supporting several projects with new codebases in my work. I have some support experience and want to say that your codebase and architecture sometimes much better and predictable then I see in my work.

Here is new compiled version for your website.