Afmformats

- docs: add section for implementing new file formats (13)
- fix: IndexError when trying to open .txt files that are no AFM files
- ref: separate submodule for formats

- enh: implement LazyMetaValue to speed-up loading JPK files
- enh: perform caching in LazyData (minor speed-up)

- fix: partially revert breaking change in 0.14.0 ("imaging mode"
was previously used when exporting data in PyJibe and this metadata
key should not change)
- fix: add detect function for HDF5 format (afmformats attempted to
load nanite rating containers)
- enh: added height span for QMap data
- tests: add .tab and .h5 test files
- ref: renamed QMap feature "lowest height" to "height base point"
- ref: changed prefix to "data" for all QMap data

- fix: populate AFMQMap grid metadata for AFM workshop format (12)
- enh: speed-up QMap computation by decorator-based caching
- ref: move QMap grid index computation to MetaData class

- BREAKING CHANGE: changed 'mode' to 'modality' throughout afmformats
- feat: introduced afmformats.AFMGroup, a container for AFMData (11)
- feat: introduced afmformats.AFMQMap for managing quantitative
AFMData (11)
- feat: allow to use other derived classes of AFMData when loading
experimental data via the `data_classes_by_modality` option
- ref: `AFMData.export` is deprecated in favor of `AFMData.export_data`
- ref: renamed submodule afm_fdist to mod_force_distance

- enh: improve speed when loading data by avoiding accessing
data during initialization
- fix: JPK file format reader speed regression caused by 10
(implemented ArchiveCache)