hack7

Created by: vloncar

This PR is the culmination of several months of development and has many changes. The ones I remember:

• tf_to_hls tool for converting tensorflow models
• Experimental support for larger Conv1D/2D layers
• QKeras support (limited to binary/ternary for now)
• API enhancements (custom layers, multiple backends)
• Profiling support
• hls4ml report command
• Support for all-in-one h5 files (obtained with Keras save() function, without the need for separate json)

• many more smaller changes I forgot.

Feedback is welcome