[PVR] Feature: Make instant recording behavior configurable

[ksooo]

This feature has been requested in at least two different forum threads.

Currently, when pressing the "record" button in Live TV OSD, on the remote control or on keyboard a fixed length recording starting "now", ending after the time set as "Instant timer duration" setting value will be scheduled.

People want more flexibility here, especially the possibility to let instant recording record the currently playing show.

This PR implements configurable instant recording behavior.

First, there is a new settings value in PVR->Recording, "Instant recordig action":

Three values are available:

• [Record current show] will record the current show from "now" to the end of the show. If no TV guide data is currently available a fixed length recording starting "now", with the value set for "Instant recording duration" will be scheduled.
• [Record for a fixed period of time] will schedule a fixed length recording starting "now", with the value set for "Instant recording duration".
• [Ask what to do] will open a dialogue containing different recording actions to choose from, like "Record current show", "Record next show" and some fixed duration recordings.

The first two options will immediately start recording without any user interaction, the third option will open a dialog with a couple of choices:

The options currently implemented for the dialog as well as the wording are only a suggestion and can easily be changed.

@da-anda we discussed this on last Devcon
@Jalle19, @xhaggi mind taking a look at the code

[ksooo]

If nobody objects I will merge this tomorrow.

[Jalle19]

Sorry for the late review, nothing critical found though.

[ksooo]

Thanks @Jalle19. I thought you already did a review.

[Jalle19]

Only did it half way the first time :-P

[ksooo]

jenkins build this please

[ksooo]

Changes requested by @Jalle19 are in.
Rebased.
Jenkins is happy.