Merge pull request #8 from xaizek/master

Prevent :LinediffReset command from failing if plugin is uninitialized
Documentation header
Settings to control positioning of splits
Allow using a real scratch buffer
ignore tags (created by :Helptags when using pathogen)
Merge pull request #10 from montefra/ignore_tags

ignore tags (created by :Helptags when using pathogen)
Ignore changes in temp buffers on :LinediffReset!