Closes #5075

Because the borders don't make much visual sense. And they cause dual
scroll bar issue when the editor takes 100% of page height.

You ca reproduce the issue here: http://mdp.tylingsoft.com/ Press
<kbd>CMD-,</kbd> to bring up the preferences panel and change the
theme to midnight.

Rather than abusing variable-3. Coloring is the same for now.

Closes #4725

This reverts commit a44e76a0.

Issue #4606

So that line widgets aren't included in the background style

Closes #4606

This prevents a selection from inheriting the default gray background when editor is defocused.

Closes #4230

Closes #4206

Usecase: Datatypes in hive are not highlighted without this fix

it seems `.cm-error` lost some specificity in [this commit](https://github.com/codemirror/CodeMirror/commit/a7d443ec82c1806d24e25ad8014a4d8651409320#diff-33646e9ee4d04eedb98a991a636c2302L35) that causes the error state to have same color as the tag.

Issue #3586

Including liquibyte theme with other themes causes other themes(when
in use) to not look right. For example there will be underline text
decorations when a text is selected in default theme.

...because the original blue on black background is difficult to read.

Also some general improvements to material.css and solarized.css