Add functions to read epoch data files (not raw data)

[vincentvanhees]

As described in #68 I am migrating code for reading epoch level data files from GGIR to GGIRread, and turned them into standalone functions for:

• ActiGraph csv
• Actiwatch csv and awd

Further, this PR adds new functions for other epoch level data file formats for:

• Actical csv
• Philips Health Band xlsx
• Fitbit json

To make this work I also created some helper functions (e.g. detectQuote.R) and listed them as internal in the documentation.

None of this should affect the previously developed functionality for reading raw data as these are all new functions tested independently.

Fixes #68

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 NEWS 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.