The Mapco theme is one of the most favorite themes (see #4295), but it has some broke UI

Before (login page)

After (login page):
The form has now the same grey background as in the configuration. Now it can uses the default form components. The width of the form is a bit wider.
The search button is not blue, when the search is not focused (the search button becomes blue, when the mouse hovers or the focus is inside the search input).

Before (registration page):

After (registration page):
same layout like the login page.
The select box has now the same size like the inputs

Before (configs)

After (configs)
The select box has now the same size like the inputs

Before (menu buttons)

After (menu buttons)
Hover background is set to a darker grey. It is now the same like the other buttons within .stick

Changes proposed in this pull request:

• clean up the (S)CSS
• delete commented out lines
• translated the French comments into English comments
• delete unused icons
• compress icons

How to test the feature manually:
see before/after screenshots

Pull request checklist:

• clear commit messages
• code manually tested