Changing GodotLightly to be more in line with GodotEngine.org

[TwistedTwigleg]

This PR contains the work I've done to try and change Godot Lightly to be more in line with the reference pages @Megalomaniak referenced in #4.

Right now the following has been changed:

• Many of the elements that were dark blue are now blue.
• Most buttons are now rectangles instead of rounded rectangles.
• Most buttons are dark blue instead of blue.
• Headers, like the forums link list below the Godot site header, are now blue instead of dark blue.
• Panels are now white instead of gray.
• The footer is now light gray with a small gray line underneath it, akin to GodotEngine.org
• When you hover the mouse over a category, the meta link text (like the username) turns from gray to a lighter gray so there is better contrast and is easier to read.
• Changed godot_coral's color so it actually reflects the color on GodotEngine.org.
• Changed the color of the box when making a new post (just below the rich post editor buttons) to be gray instead of dark blue. This makes the dark blue buttons visible again.

There are a few things that need addressing now that these changes have been made:

• [x] When the cursor is over a discussion, the gray meta text is almost impossible to read. -- Fixed!
• [x] Some buttons still need adjusting so they are rectangles instead of rounded rectangles. -- Fixed
• [x] Fonts probably need to be changed (maybe?) -- Probably better left to another PR.

There are probably other things I have forgotten to add to both lists! I'll try to update the lists as I go.

[TwistedTwigleg]

Okay, I added some new things and I think this PR is ready to go. Here is what I changed in the last commit:

• When you hover the mouse over a category, the meta link text (like the username) turns from gray to a lighter gray so there is better contrast and is easier to read.
• Changed godot_coral's color so it actually reflects the color on GodotEngine.org.
• Changed the color of the box when making a new post (just below the rich post editor buttons) to be gray instead of dark blue. This makes the dark blue buttons visible again.

I also updated the post above to reflect the changes. Here is a screenshot to show how the theme looks with these changes:

@Megalomaniak, does this conflict with the changes you are making? If it does, we can wait and then update this PR if needed to be compatible with any changes you've made. Just let me know if you want me to wait with pulling this PR in or not.

[Megalomaniak]

No it shouldn't. Go ahead.

[TwistedTwigleg]

Okay, in that case, I'll merge these changes in!