tweak documentation
  * added global option to display the reason for building a target
  * fixed custom build rules executed twice sometimes
adjust to D_parser changes
installer: fixed some texts, append "dmd2" to path from D installer
  * improved indentation after opening parenthesis to follow next token
  * added commands "Collapse unittests" and "Collapse disabled" to the outlining menu
  * started work on displaying coverage margin
removed Mixed/Any platforms from solution
Merge pull request #7 from rainers/master

transfer to dlang.org