Improve tooltip text and layout

[dlangBugzillaToGithub]

r.sagitario (@rainers) reported this on 2018-11-03T08:46:00Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=19355

Description

from https://forum.dlang.org/thread/imrhiouthncheeekksny@forum.dlang.org:

• Tooltips on token-string literals adds a lot of extra spacing between symbols.

• Tooltips that show documentation can have excessive line breaks.

• Tooltips on variables repeat attributes - eg, "private int length;" produces "private private(int) [parent].length" instead of perhaps "(variable) private int [parent].length".

• C#-style formatting and colourisation in tooltips.