transplant: change "editform" to distinguish merge commits from others
"editform" argument for "getcommiteditor" is decided according to the
format below:
EXTENSION[.COMMAND][.ROUTE]
- EXTENSION: name of extension
- COMMAND: name of command, if there are two or more commands in EXTENSION
- ROUTE: name of route, if there are two or more routes in COMMAND
This patch newly adds "normal" and "merge" as ROUTE, to distinguish
merge commits from other.
This patch adds 4 test patterns to test combination of "merge"(x2) and
"--continue"(x2).