Jump within the same instance of mutt

I've added the possibility to invoke the script as muttjump-same. When used this way, it will just create a file with commands for mutt to jump on a desired message. This file can be easily sourced by mutt within a macro. That enables following workflow:

1) Search for a message from mutt by using some indexer
2) View the results and select the right one
3) Jump on the original source of that message in the same instance of mutt
4) Proceed with further work (it is not necessary to quit any mutt's instance)

Note: I've tested it just with notmuch, but AFAIK this should be indexer-independent.

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In the source, there are no deletions - just additions (and modification of the line with the name of the script). However, a block of code has increased indentation, since now it is nested into an if/else block.