add SET-ENV, tweaks to host api for environment string handling
Fix spaces-instead-of-tabs that slipped into /src/os/posix/host-lib.c
Update src/boot/actions.r

Corrected misspelled word in head?  definition; 
from 
begininnt
to
begininng
fix a typo
Match  "uncased" parse in Check_Bit by inverting HAS_CASE(parse)
Fix crash when reading dns:// without a hostname

Previously, `read dns://` crashed the interpreter. With this fix, a
dns:// spec without a hostname (or IPv4 address) is considered invalid
for READ access:

    >> read dns://
    ** Access error: invalid spec or options: dns://

Fixes the crash reported in CureCode issue #1935.
Allow INDEX? of NONE, returning NONE

This makes INDEX? "NONE-transparent", in line with the already
none-transparent EMPTY? and LENGTH?:

    >> index? none
    == none

This implements CureCode wish #1611.
Remove redundant code

The A_INDEXQ and A_LENGHTQ cases would already fall through to A_TAKE
containing precisely the same `if` (making the `if` redundant in case
the condition is true) and then falls through further to the `trap_it`
block (making the `goto` redundant in case the `if` condition is false).
Move NONE! to end of INDEX? & LENGTH? typespecs
parse thru fix
bug#1939
Merge pull request #58 from angerangel/master

Corrected mispelled word
Merge pull request #59 from blackball/master

Fix a typo when typedef uint
Merge pull request #60 from earl/fix-parse-thru

Fix a regression in PARSE for the THRU keyword
Merge pull request #61 from hostilefork/fix-mem-errors

two memcpy to memmove changes, fix use of uninitialized err value
Merge pull request #63 from hostilefork/parse-bitset-casing

Match  "uncased" parse in Check_Bit with !HAS_CASE(parse)
Merge pull request #55 from hostilefork/set-env-updates

add SET-ENV, tweaks to host api for environment string handling
Merge pull request #64 from earl/fix-op-eval

Fix crash in evaluation of immediate operators (op! values)
Merge pull request #66 from earl/fix-empty-dns

Fix crash when reading dns:// without a hostname
Merge pull request #67 from earl/allow-index-of-none

Allow INDEX? of NONE!