vimPlugins.vimshell: add expression
vimPlugins.vimproc: add expression
close #978
Net-SNMP: disable tests
fix tarball test
Manual: Update installation section
nix-gc: Revert to "script" instead of ExecStart

There is an assumption that cfg.options can contain shell code, so
ExecStart doesn't work here.
e2fsprogs: Update to 1.42.8.
mailman: add version 2.1.16
xserver.s3tcSupport: fix typo, improve description.
postgresql.authMethod: remove unimplemented option.
close #1104.
perlPackages.GnuPG: new expression
perlPackages.LocalePO: new expression
perlPackages.TAPParserSourceHandlerpgTAP: New expression
perlPackages.TemplatePluginJSONEscape: new expression
Close #1103.
Make 1.6 the default Wine version and call 1.7.4 wineUnstable