Feature - version 4.0.0, do minimal SRAM content dump in circuit file

[MatNieuw]

The 3.3.x / 3.4.x versions used a straight text file for circuits, and dumped SRAM content without trailing zero entries, so when the circuit was loaded, all SRAM was zero except for those bytes from the file.
The 4.0.0 version used a handy xml format for the circuit file, but dumps the complete SRAM content. So if I have a 2048 byte SRAM, with initially only 32 bytes filled, I still get the full 2048 bytes dumped in the file. So with for instance 11 SRAMS this takes a lot of lines in the circuit file.
Please add the 3.x behavior of not storing the trailing empty bytes for a SRAM.

[pfalstad]

We only dump 0 bytes if the 0 byte has been written to memory or loaded from a file. I don't think this has changed since 3.3.x. It can be fixed though.

[MatNieuw]

I stand corrected. I converted a 3.4.1 circuit to 4.0.0 , and discovered the large SRAM content. It appears that this particular circuit did have 2k bytes written to SRAM, so the resulting large file was not because of the 3.4.1 to 4.0.0. format conversion. The layout of the xml file format simply made it more obvious.
I greatly appreciate your change to do sparse SRAM dumps!