Feature: Smart case sensitive searching

[DerpMcDerp]

Here is how the "smart case sensitive searching" option should work:

1. If there is at least 1 uppercase character in the search field, the search should be treated as case sensitive. Otherwise the search is treated as case insensitive.
2. When the ctrl+f is pushed and there is a text selection, the edit field should be tolowered such that there are 2 strings in the edit field's undo history - the current lowercased one and the previous original cased one. If the user desires to use the original casing, they can just push ctrl+z to undo. This is only done if the selection contains at least 1 uppercase character.
3. When pasting and case insensitive searching is active, the pasted text should be tolowered such that there are 2 strings in the edit field's undo history - the current lowercased paste and the previous original cased one. If the user desires to use the original casing, they can just push ctrl+z to undo. This is only done if the pasted text contains at least 1 uppercase character.
4. The "Match case" button should indicate whether or not case sensitivity is active determined by the text in the edit field. Pushing the "match case" button lowercases the text in the edit field. The empty field is treated as case insensitive (so pasting defaults to case insensitive).

[Quicksaver]

Don't hold your breadth for any of this. Something as complex as this actually brings very little benefit, in only a few very specific use-cases. This will be very low in the priorities list, after pretty much every other thing to be done.