Set default output filename to match base path of input

[kspaceKelvin]

This sets a default output filename to match the input name so that it's easier to use.

@hansenms If you have a cleaner way of implementing, please suggest it.

[hansenms]

Please merge in the master branch.

I could not from fast searching find a quick way to set a default value from another value in boost options, so maybe it is not possible. @dchansen do you have experience with this? This is not the end of the world here, but it just feels a bit ugly to set the string empty (and so default value which shows up in the help text is empty). but then when the default value is the default value, we actually overwrite it, so it is not the default. Seems bad.

[kspaceKelvin]

Are you asking me to merge into the master branch of my fork? I thought GitHub would have figured out the diff now that the skipSyncData PR has been merged, but I still see it in the diff here. I'm evidently not wise in the ways of the GitHub...

[hansenms]

you need to merge master into your branch...or rebase your branch, whichever you prefer. If you rebase, you may have to force push, so I would merge the master.

[hansenms]

If we cannot find a way to specify the default in terms of another parameter, I would recommend setting the default to something like <input file without extension>.mrd so that it shows up in the help text and then replace that.

[kspaceKelvin]

Ah, ok, I fetched the upstream and we're good. Let's wait for David to comment on if it's possible to directly set the default value as you suggested.

[hansenms]

Looks good.