Rename signals and ops relevant to save-commit units

[shundroid]

Currently the name of signals and ops is difficult to understand.

After the discussion with Emmet, we decided to change them.

• branchDiscardNonSpec → branchDiscardCondNonSpec (since two signals of condition and control involve in save-commit units)
• branchDiscardControlIfPass → branchDiscardCondNonMisspec (control was wrong. IfPass was difficult to understand)
• branchDiscardControl → branchReplicated (more common name, which indicates the branch replicates the original branch in the data network)

And for signals

• SCBranchCtrl → SCIsMisspec (briefly describe what the signal is about)