Edalize 0.4.0

• New backends: OpenFPGA, VPR, Mistral, gatemate
• symbiflow: Support Quicklogic
• xsim: :Fix VHDL generics quotation
• ISE: Added option to Specify JTAG chain index, fix windows path handling
• verilator: Support EDALIZE_LAUNCHER, limit CPU usage
• icestorm: Add icepack_options
• el_docker: Run as user instead of root
• vcs: Support boolean plusargs without value
• yosys: Support verilog output
• Flow API: Add get_tool_options function