files.cf: set_config_values changed to support special RHS chars and smarter operation

Changed set_config_values to support special characters in the RHS (so we don't confuse the regex on expansion) and:
1. if LHS exists with the wrong value correct it, else
2. if LHS is commented out and #1 did not apply, uncomment and correct, elst
3. if #1 and #2 did not apply, append it

Plus other fixes.  See https://github.com/cfengine/masterfiles/pull/4
lib/3.6/files.cf: add set_config_values acceptance test
Merge pull request #53 from tzz/ed45626/feature/improve-file-editing

files.cf: set_config_values changed to support special RHS chars and sma...
lib/3.[56]/files.cf: add set_variable_values acceptance test
.gitignore: add tests/acceptance/testall.env
lib/3.6/files.cf: add set_line_based with acceptance tests and deprecate many others
Merge pull request #99 from tzz/feature/set_line_based

lib/3.6/files.cf: add set_line_based with acceptance tests and deprecate many others
Add path to realpath for debian, redhat and freebsd
Add cron, snmp and newsyslog service entries for FreeBSD
Merge pull request #100 from skreuzer/realpath

Add path to realpath for debian, redhat and freebsd
Merge pull request #101 from skreuzer/snmp

Add cron, snmp and newsyslog service entries for FreeBSD
Merge pull request #98 from mmuensch/master

added path variables of commands from suse and solaris
Add documentation for freebsd{} and freebsd_portmaster{}
Update packages.cf

Fix ordering per @tzz request (I hope I understood correctly!)
Fix typo (extra CRs) in lib/3.5/packages.cf, add documentation to
lib/3.6/packages.cf for freebsd{} and freebsd_portmaster{}.
Redmine#3617: document package_method emerge
Redmine#3617: document package_method alpinelinux (apk)
Revert "Deprecate `admit` constraint"

This reverts commit 9e3cd5768ce549cbb5dfcd0a57541e8040cb1595.
update: introduce and use u_def.masterfiles_perms_mode
inventory/any.cf: dmidecode bundle should respect disable_inventory_dmidecode