* add back ability to create transform with loader
* change 'samples' -> 'examples' for tfds wrapper to match tfds naming
* add support for specifying feature names for input and target in tfds wrapper
* add class_to_idx for image classification datasets in tfds wrapper
* add accumulate_type to avg meters and metrics to allow float32 or float64 accumulation control with lower prec data
* minor cleanup, log output rate prev and avg
* Add parser/dataset factory methods for more flexible dataset & parser creation
* Add dataset parser that wraps TFDS image classification datasets
* Tweak num_classes handling bug for 21k models
* Add initial deit models so they can be benchmarked in next csv results runs
* refactor 'same' convolution and add helper to use MixedConv2d when needed
* improve performance of 'same' padding for cases that can be handled statically
* add support for extra exp, pw, and dw kernel specs with grouping support to decoder/string defs for MixNet
* shuffle some args for a bit more consistency, a little less clutter overall in gen_efficientnet.py
* reorganize train args
* allow resolve_data_config to be used with dict args, not just arparse
* stop incrementing epoch before save, more consistent naming vs csv, etc
* update resume and start epoch handling to match above
* stop auto-incrementing epoch in scheduler