launching help viewer

Under *nix systems, if we can't find the direct location of docview, we
try the 'which docview' command. If we get a positive response, we know
docview is in the system path, and we can go ahead and launch it.

At least this doesn't instantly throw an exception when docview can't
be found on the first attempt.
New SearchMode property to FileListBase class

This allows the developer to filter the file results by Files only,
Directories only, or both (default).
Merge branch 'dibo-searchmode' into develop
version bump for develop branch
Merge latest fixes from 'release-1.0' branch into develop
Merge branch 'release-1.0' into develop
Merge branch 'hotfix-1' into develop
docview: To make sure TotalSize is > 0
minor code cleanup
New record structure to be used in future OnMove events.
MDI: work area now has a CascadeWindows method.
MDI prototype: fixes code to remove compiler hints
MDI child windows now have a OnMove event
MDI prototype now has basic horizontal scrollbar support.
MDI prototype: demo project now uses the Cascade Windows functionality
MDI: fixed editor settings screwup. Converted Tabs -> Spaces
Merge branch 'mdi_horizontal_scrolling' into develop
Adds a simple Git HowTo document

I frequently get asked some Git questions. So hopefully having a quick
reference document will help some developers. It also gives me
something to quote in emails. :)
Merge branch 'hotfix-2' into develop

I found a problem with the deadkey support - it broke keyboard input under
Windows. The original deadkey input issue seems to have been X11 specific,
so should be fixed at widget level, but rather in the fpg_x11.pas unit.
Grids: improve UpdateScrollbars for resizing etc