Change encryption UI labels and clickability

[funnel]

In a ​thread about the encryption preferences:

Cas wrote:The 'Encrypt Entire Stream'... relates to choosing 'Either' level of encryption.... The label should probably be changed to reflect this, such as 'Prefer Full Stream Encryption', so this option should be greyed out unless the dropdown option 'Either' is selected. The alternative is to simply set 'prefer_rc4' internally in Deluge to default True as I imagine most users would be happy with that or would not care.

If both Inbound and Outbound encryption are set to disabled, then this would be the only point that 'Level' and 'encrypt entire stream' should be greyed out, so this could be changed for clarity but is a trivial issue.

I vote for setting 'prefer_rc4' internally to True. If 'Either' is selected, it doesn't make sense to me for 'Handshake' (the less secure option) to ever be preferred over 'Full Stream'. Offering the option to do so seems pointless because 'Encrypt Entire Stream' already contains a fallback mechanism to 'Handshake' , and it is potentially confusing when seen alongside the 'Full Stream' dropdown option.

I also agree with the second point to grey-out the Level dropdown when both Inbound and Outbound are 'Disabled'. This makes the relationships of the options easier to visualize for the user.

[Cas]

Fixed in develop: ​7bd53903a425ec

[Cas]

Milestone renamed