[ShowImage] add Get info shortcut (easy)

[diver]

It would be nice to be able to press Alt+I to get Tracker's info window regarding currently displayed image.

[artcodex]

Adding Get Info to show image tool

[artcodex]

I wanted to take this on as a good started issue to look at as I'm new to Haiku. I didn't realize the exact process yet, but started looking at this, just to get my feet wet in the source code and the system. Hopefully this item is still up for grabs. I added a patch set of the work I've done so far for this.

[waddlesplash]

Looks like your coding style doesn't conform to our guidelines (​https://www.haiku-os.org/development/coding-guidelines). Also, your commit message should contain the name of the app ("ShowImage") first, followed by a colon, and a complete sentence ending in a period. The ticket number should be in the body of the commit details.

[pulkomandy]

More complete code review:

• Indent with tabs (4 columns per tab)
• I would try to fit the menu item in one of the existing parts of the menu (maybe just under "move to trash"?). Putting it in its own section between two separators isn't useful.
• Two blank lines between functions
• Why inserting the method declaration between PrepareForPrint and Print? These two sould like they should stay together in the group of "printing" functions.

[artcodex]

Updated to conform to code review guidelines and with fixes

[artcodex]

I updated the patch to conform to coding guidelines and with above suggestions for better placement. Also updated the commit message. Let me know if there is further feedback.

[pulkomandy]

Applied in hrev50087. Thanks!