Prevent OutOfMemoryErrors from the UI when switching CMV

When comparing models that have very large single references (one
reference containing 30k or more elements), computing the LCS will
consume a huge amount of memory, repeatedly, only to display a
placeholder for the insertion index if the user chooses to merge a
given difference. This commit limits the number of object

Change-Id: I4a18385090daf3d788c0f4a81faf470d526d4e42
1 file changed