Minor refactoring

I've done some minor refactoring of the db.php file and the parser.js file. As well, I've done some documentation fixes.

Made the uploading of assembly language programs work in WebPositive

In v4.0.1, there was a bug preventing the uploading of assembly language programs work in WebPositive. I fixed it and I am therefore making a new release.

Fixed a bug related to the handling of new-line characters

The handling of the new-line characters now seems to work correctly in both Firefox and Chrome. I simply replaced textContent with innerText in the code written by @betelgeuse-7 and it seems to work now.

The first version of the back-end

Thanks to the help from @betelgeuse-7 , if this program is run on a server with PHP and MySQL available, it is now possible to share PicoBlaze assembly programs.

Made it use more Bootstrap icons and less ASCII art

I've made my PicoBlaze Simulator use more Bootstrap icons instead of ASCII art.

Fixed a bug causing the preprocessor to fail silently if somebody misspells a directive inside an if-branching or while-loop

When I was modifying the Preprocessor Test, I noticed that the preprocessor fails silently in case the user misspells a preprocessor directive inside an if-branching or a while-loop. So, I fixed that.

Fixed a bug making the licence illegible in Firefox 52

GitHub's front-end has changed and the licences stored on GitHub are no longer legible in Firefox 52 (#22 ). So, I changed the link in the banner to point to SourceForge rather than to GitHub.

Fixed a bug causing unclear error messages

I've fixed the bug #21 , which was causing unclear error messages if jump was used improperly.

Refactored the preprocessor a bit

I have refactored the preprocessor a bit. Also, I have made the assemble function in the file assembler.js check whether its first argument is actually the root of the abstract syntax tree. And some other small details... The functionality should remain the same.

Refactored the HTML a bit

I have extracted the SVG of the Stop button into a separate file.