add icons
fix items with IconBrowseFileExplorer
use different icon for IconFileTree
FormBrowse: Diff tab: add item "Show in File tree" to context menu
FormBrowse: Diff tab: context menu: fix two captions
DiffContextMenu_Opening: refactoring: rename local variable; do file existence check without using return.
FormBrowse: Diff tab: context menu when several items selected: disable items that are not suitable for multiselection
FormBrowse: basic implementation for "Show in File tree" context menu item click
FormBrowse: "Show in File tree" directly goes to the file instead of expanding the whole tree.
FormResolveConflicts: add Goto Help link
GotoUserManualControl: fix url generation
GitUI: make internals visible to the GitExtensionsTest project
Add unit test for GotoUserManualControl
GotoUserManualControl: fix GetUrl
Submodule GitExtensionsTest updated

Submodule GitExtensionsTest:
    > 48dd549 - Corrected encodings.
    > 7399c9a - comparing text without encoding
    > d3e6614 - removing lossless encoding, using UTF8
    > 1500d2e - Removing unnecessary small.patch file, moving creation of small patch to a method, using losslessEncoding
    > 04de8d1 - Adding back TestPatch
    > 185cb25 - Remove unused debug statement
    > 63ce1f1 - Loading patch from expectedPatch
    > 079abdc - Revert "Ignoring Translation test for mono"
    > b383614 - Ignoring Translation test for mono
    > 231d828 - Correcting TestContext not implemented in mono
    > 744b284 - Increasing tests for PatchManager
FormSettings: show Discard button only in Debug mode. Update hint text.
FormSettings: fix minor "jumping" of button row when hint text appears or disappears
FormBrowse: add "go to current revision" to Commands menu
Merge pull request #1859 from feinstaub/fix_remove_discard_button

FormSettings: show Discard button only in Debug mode
SelectCurrentRevision: add ShortcutDisplayString from settings to menu