{evolve,topic}: improving synopsis strings of commands

This is a quick pass over commands from the two extensions (except debug commands) to see if the first line of hg help cmd can be improved.

Everything should be self-explanatory. Even though this string is just for users only, it has some rules (or, rather, conventions). For example, metavariable for a revision is REV, for a file is FILE, etc. If an option can be provided multiple times (e.g. revision), it has an ellipsis after it: -r REV.... Optional parts (including whole options) are given in square brackets, e.g. [[-r] REV] means not only specifying a revision is optional, but it can be specified either with -r or without it.