Issue983 axis qcplot edits vincent

[vincentvanhees]

@jhmigueles In this PR I propose a couple of edits to PR #985

• Renaming of object names to improve readability
• Fixed day numbering, which missed the first incomplete calendar day. This is now accounted for.
• Your change to argument mar caused y axis to overlap for devices with temperature data.
• I replaced d1, d2, d3, etc by a single axis label "recording day" and then all the numbers at the axis.
• I changed x-axis font to 1 to be in line with y-axis, similarly the hash area for study protocol, and accelerometer signal has thinner lines now. I do this as pdf files tend to be smaller with thinner lines, which becomes an issue if the user creates thousands of plots like these. Also, I am trying to avoid inconsistent line width when there is no functional value of the differences.
• minor edits to legend to clarify that by 'study protocol' we refer to the masking of time. I had to keep it short as there is limited space.
• Replaced repeated calculation of day length, which by the way also was problematic as you were calculating this on a vector with possible length of one if recording has only one noon or midnight. Further, this number would be incorrect if there is a day in the recording with 25 hours.
• UPDATE: Now horizontal axis simplified as vertical grid already clarifies when noon occurs, so no need for ticks

Example 1:

Example 2:

Checklist before merging:

• Existing tests still work (check by running the test suite, e.g. from RStudio).
• Added tests (if you added functionality) or fixed existing test (if you fixed a bug).
• Updated or expanded the documentation.
• Updated release notes in inst/NEWS.Rd with a user-readable summary. Please, include references to relevant issues or PR discussions.
• Added your name to the contributors lists in the DESCRIPTION file, if you think you made a significant contribution.

[vincentvanhees]

Actually, I think the double axis does not serve any purpose because the vertical lines already clarify when noon and midnight is. I will now make an extra commit to remove the double axis such that we only have one axis to indicate the midnights

[vincentvanhees]

I just made a few minor edits. The grid lines now cover all plots and the legend is more clearly positioned on top. To illustrate how it looks like with all masking types I simulated some clipping in the example I show above, which now looks:

[jhmigueles]

Looks great! Just a couple of minor comments to make the y axis labels always perpendicular to the axis in all plots (ACC, temperature, and nonwear score). No further comments beyond that. Thanks!