MicroTESK

Some template features seem to be common for all ISAs, e.g.,

1. riscv_base.rb: constants NAN, INF, etc (IEEE 754);
2. riscv_base.rb: data definition directives .byte, .hword, etc (GNU assembler).

I suggest introducing template libraries such as

1. float.rb and
2. gnu.rb

to avoid copy-paste.