Allowing char '%' to be escaped in the format column

[bluelionet]

Hi!

I fount that in some cases it's not possible to write format using % while not making it to be interpreted as predefined variables.
For example, if I literally want to include a string "%title%" in the format, it cannot be done because every time I use this format to copy things, the %title% will always be replaced to the page title (but I actually just want the pure string "%title%"!)

Possible solution may be allowing char % to be escaped in the format column, for example, maybe %% will be interpreted as a char %. In the previous case, I can then just write %%title%% to get what I want.

Please consider this request.
Also thanks for the great work!