IDEA-131993 Debugger: arrays/collections: "more items" specifies wrong value

(cherry picked from commit 2b15af802372eea188dd7e3e6fc20b086543c0c8)
remember corresponding XDebugProcess in DebugProcessImpl

(cherry picked from commit 20938f8638bcd826ca1788c1d5e8ab189a6d92b1)
remember corresponding XDebugProcess in DebugProcessImpl - fixed tests

(cherry picked from commit 49e89d6c253cadc80154161bd4cae2a7906b77c8)
IDEA-125322 Debugger: F2 adds new row in Watches

(cherry picked from commit 3699912a7a6f6dfcb263ae25d6fe6bc7d2f380a9)
fixed broken shortcut for next task window action
(cherry picked from commit 89fbb33)
fixed EDU-260 Course description edit field wrong behavior
(cherry picked from commit a681e95)
fixed ipython notebook cell resize.

Now we use vertical flow layout instead of grid bag layout. Editable cells are self contained so we have invisible prompt labels in them.
(cherry picked from commit 941efb7)
produce less trash objects

(cherry picked from commit 474dd67a8d169293360d3d86db54b7ff90c44c8d)
replaced task window with answer placeholder in some string literals
(cherry picked from commit 50f7c79)
renamed task windows to answer placeholders for python code
(cherry picked from commit 23956b4)
Merge remote-tracking branch 'origin/139' into 139