Use the same color for all delimiters in the window

[ProgerXP]

The main window has at least 6 kinds of thin solid delimiters: below the main menu, below the toolbar, between the toolbar buttons, above the statusbar, to the right of the line gutter, to the left and right of the text area (the hard to notice white border, apparently belongs to Scintilla). All of these except the last two should be made the same color (#D7D7D7).

Also consider making line gutter background and splitters uniform.