Add 'minlen' option for topo graphs

Running build_topo_graph.pl with -m 2 increases the spacing between the
nodes and makes it less likely for the interface names to overlap.

Fixes redmine #1821 if you update your topo crontab entries to add -n -m 2
Add line length setting in device topo view

Makes it easier to see interface names if "Show Interface Names?" has
been selected
Options for rebuilding whole topo graphs

Add options 'Show Interface Names' and 'Line Length' when rebuilding the
whole topo graphs in the GUI

Fixes redmine #1821
Fixes for #1818
Swap head/tail on "up" links

Previous change for #1824 ended up with head/tail labels on the wrong ends
Merge pull request #20 from candlerb/candlerb/1821

Improvements to topology graphs
Merge pull request #21 from candlerb/candlerb/1822bis

Swap head/tail on "up" links
Fix for #1791 (Exclude static IP information from prune_db.pl's IP address pruning)
Fix for #1809 (UI bug when viewing BGP peers)
Fix for #1809 (UI bug when viewing BGP peers)
Assignment of colors to VLANs

* Don't include arbitrary (database id=1) VLAN in topo display
* Assign vlan color from VLAN vid algorithmically

Fixes redmine #1827
Merge pull request #22 from candlerb/candlerb/1827

Assignment of colors to VLANs
fix for 1765
Merge remote-tracking branch '42wim/fix-1765' into fix-1790
Merge branch 'master' of github.com:cvicente/Netdot into netdot-1.0