reorder-columns

Added a new function `reorder-columns` for a dataset that will change the order of appearance of the datset columns.  It does not alter the row order.

This should help with the conj-rows issue in #78
Fix column names for dataset construction from map

column names were mixed up when constructing a dataset from
a map, this has been fixed by introducting a transpose
Updated the ClojureTv channel from blip.tv to youtube channel
Return permutation matrix in LU decomposition.
Merge pull request #134 from nblumoe/master

fix column names when constructing a dataset from a map
Merge pull request #135 from srinivasreddy/master

updated the clojure tv  channel to youtube.
Merge pull request #136 from nbeloglazov/lu-fix

Return permutation matrix in LU decomposition.
Added a new option to heat-map - :include-zero?

When :include-zero? is false and the origin is not in the range of
the plot, the origin will not be included in the plot, and the
ranges will simply be the supplied data ranges.
Merge pull request #137 from JackSullivan/upstream

Added a new option to heat-map - :include-zero?
Added documentation for :include-zero? option in heat-map. Also filled
out the docstring for heat-map to match other chart functions.
Merge pull request #138 from JackSullivan/upstream

Added documentation for :include-zero? option in heat-map.
add "tail" function
fix typo
support negative lengths
Merge pull request #140 from farrellm/tail

Fix for issue #139
update dependencies, use fresh clojure version
Merge pull request #133 from davidjameshumphreys/align-data-cols

reorder-columns
rewrite reorder-columns more idiomatic way, using the sel
add-* functions should return chart object

this should fix #141