introduce new static method isEnabled
add "Check for Update" action to the new welcome screen
Mark dirty & batch refresh VirtualFiles instead of refreshing on-by-one

Fixes IDEA-120150, IDEA-115773
(cherry picked from commit 14cf1bc)
[vcs] IDEA-119375 assign shortcut to "Move to Changelist" only if not found in keymap

(cherry picked from commit f6008a3)
[vcs] IDEA-131714 copy full revision number at least until the option
is available for user and/or we guarantee that the short hash we
give is enough.

(cherry picked from commit cc21d5c)
[log] more debug info for "no references pointing to head" error

Check if GitLogProvider returns sync data
(cherry picked from commit 6d96f36)
[git log] Load first commit block always with refs

To avoid desynchronization when refresh starts from scratch.
(cherry picked from commit 0062ad3)
[git] IDEA-130660 Don't allow empty or spaces branch names
(cherry picked from commit 6f950bd)
IDEA-58130 Improve editor performance during working with large files written in a single line

(cherry picked from commit 9ea26bc614c1f9add7255f5639b894a9f0c9a4ee)
refactoring (following CR-IC-6668)

(cherry picked from commit 50b087323799204fdb4d8e0a51e52526d5572bd5)
IDEA-131521 Provide unified capitalization

(cherry picked from commit 8be90ffb9e1f7156d51f9b404cdbfc7591691f82)