Version 0.6.2.0

Mostly consisting of bugfixes and stability improvements.

• Function previewer in the mixed-asm-data window:
  
• Added support for Wii and RT-11 platforms
• Added support for RT-11 LDA and SAV files, and Nintendo DOL files.
• Add support for custom loader. Users can provide their own front-ends to Reko.
• Support for parsing GCC symbols
• Added support for Atmel AVR8, Risc-V, and Xtensa AVR8 processor architectures
• Added [[reko::arg(fpu)]] C++-style attribute
• #213: more work on the jump table dialog

Thanks to @ptomin, @a2intl, @Lukas-Dresel, @MeFisto94, @rogersachan, and @smx-smx for their contributions