Fix a race i noticed while pondering #1500:  We must snapshot the
object length while processing the Range header to ensure consistent
results when streaming from the backend.
Prefix the C-symbol of VCL objects with "vo_" to avoid issues with
reserved C keywords.

Fixes #1498
Make our Via header RFC compliant.
Deref the old object after finishing with it in cnt_miss()

Fixes: #1499
The vcl_purge{} method can return synth or restart.

(Remember to change the "PURGE" to "GET" if you do this.)

Fixes #1493
Fix typo.
Document that obj.hits may behave differently.
Backtrack advice that bit during testing.
Cope with systems having both <sys/endian.h> and <endian.h>

Fixes:	1476
By default linux::getopt(3) mangles the argv order, such that

	varnishadm -n bla param.set foo -bar

gets interpreted as

	varnishadm -n bla -bar param.set foo

This is counterintuitive and invites random script breaking if people
don't know they have to add an ornamental '--' in front of the CLI command
in Linux systems.

This commit makes Linux work the same way as every other POSIX system.

Fixes	#1496