fix #241: cover another case of instruction encoding convergence failure

add test variants for driver options

remove string type distinction

fix asm block substitution

bump version up

resolve #236: indicate when the binary or annotated outputs are padded with zeroes

fix slice spans

resolve #235: add special parsing for glued integers

improve web page

error on reserved name use

resolve #230: add option for $-prefixed built-in names

Allow colon symbol for ruledef

fix #232: remove leftover debug code

add the `readmemb` and `readmemh` output formats

fix #229: prevent duplicate instruction matches as early as possible