Fix and cleanup logic related to frames

[pekkaklarck]

There are currently several problems with handling frames that should be resolved. Some of these problems are already covered by existing issues, but this new issue list all these highly related problems in one place. The whole frame handling logic should be rewritten and all these problems resolved at the same time.

1. Page Should (Not) Contain searches text from frames, but only searches from one level and not from sub frames (Inconsistency in page/frame related keyword #98)
2. Other keywords don't look inside frames at all. This includes Page Should (Not) Contain Element and Current Frame Should (Not) Contain. (Inconsistency in page/frame related keyword #98)
3. Page Should (Not) Contain internally selects the main frame, disabling earlier Select Frame calls.(Select Frame Keyword behaviour #201)
4. We should see could we deprecate all Current Frame ... keywords. It would be better that after selecting a frame, all subsequent keywords would operate in the frame. This may actually already be the case, except with Page Should (Not) Contain which looks from the root (see 3. above).
5. If all keywords operate on the selected frame, Page Should is pretty misleading wording. Should we consider renaming these keywords like Page Should Contain -> Text Should Be Present, Page Should Contain Element -> Element Should Be Present?

[mcleanmds]

Additionally to the problems already listed, there is a similar problem with the Frame Should Contain Keyword, the driver is switched back to the default context, which is undesirable when working on sub frames. (expected to end up at the window/frame that we started from, not the main window).

[tmaleckiplacester]

Any update on this one?

[aaltat]

There is not progress for this issue because no-one has seen it enough important to invest time.