Enhance keyboard consistency on macOS

[dieterdreist]

I know this is a topic which already was discussed some years ago, but the current situation is really confusing for every mac user, because of the strange keyboard implementation.

Usually on a mac there are 2 possibilities when using software: the author has taken special care for mac users and the Command ⌘ key is mapped to mac standards (e.g. ⌘+c for copy), or they haven't and you will use the CTRL key.
The strange behaviour of JOSM is that some actions are mapped to command, e.g. copy an object is ⌘+c, paste tags is ⌘+SHIFT+v, undo is ⌘+z, and most key combinations (according to the preferences it is all custom combinations), but unfortunately there are still a few which aren't:

For example to copy text in forms, like tag values, you must use CTRL+c, to cut CTRL+x, to paste text CTRL+v, to select all text CTRL+a, to rotate objects CTRL+SHIFT, to scale CTRL+ALT, and maybe there are some more.

This mixed behaviour, especially the CTRL+c to copy text is extremely unusual and even after many years of intensive JOSM use still hits me from time to time.

[dieterdreist]

For reference, this is a ​list of default OSX shortcuts, you can see that "CTRL" isn't used on macs (you use it only in the terminal, or to use terminal commands in input fields, like CTRL+a to jump to the start of the line).

[Don-vip]

Status report from #16157:

Identification: JOSM/1.5 (13595 en) Mac OS X 10.13.3
OS Build number: Mac OS X 10.13.3 (17D102)
Java version: 1.8.0_144-b01, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM

[Don-vip]

Can you please check with Java 10?

[dieterdreist]

I can now confirm the situation is the same with java10:

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2018-04-08 14:43:17 +0200 (Sun, 08 Apr 2018)
Revision:13609
Build-Date:2018-04-09 01:32:11
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (13609 en) Mac OS X 10.13.4
OS Build number: Mac OS X 10.13.4 (17E199)
Memory Usage: 308 MB / 2048 MB (90 MB allocated, but free)
Java version: 10+46, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: Display 188875522 1920x1080, Display 458628992 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-Dsun.java2d.opengl=true]
Dataset consistency test: No problems found

[simon04]

In 17775/josm:

see #16158, fix #20759 - Command+C to copy tags from properties dialog does not work on macOS

[simon04]

In 17776/josm:

see #16158 - Use Command+Enter for main dialog action on macOS

[simon04]

In 17777/josm:

see #16158 - DownloadDialog: fix parsing bounds on Command+V on macOS

[simon04]

In 17779/josm:

see #16158, fix #12856 - Keyboard shortcuts for zoom out/in not working on macOS

Remove Shortcut.registerSystemShortcut for "view:zoomin" and "view:zoomout"

Ref: ​https://support.apple.com/en-us/HT210978