Fix infinite loop problem in iedit-rect-mode
Also add a new test case
Add overlay priority option
complete iedit-toggle-selection
Remove confusing messages "Locate the fist occurrence"
Fix failed testcases
ensure iedit-skip-modification-once is t in case of errors
Merge pull request #35 from lewang/ensure-skip-mofication-once

ensure iedit-skip-modification-once is t in case of errors
Split iedit-occurrence-update into two functions