Switch default scoremats to explicitly check option
refactor fc_subscoremat to use nat.nblast::sub_score_mat

* closes #22
remove internal diagonal function

* now in nat.nblast
move test for diagonal() to nat.nblast

* since the function has been removed
fix: make sure hclustfc attaches scoremat if reqd

* was not attaching the scoremat defined in options("flycircuit.scoremat")
  but assuming someone else had already done this.
test that we can cluster using scoremat in options
Merge branch 'fix/cached-nblast'

* fix/cached-nblast:
  test that we can cluster using scoremat in options
  fix: make sure hclustfc attaches scoremat if reqd
  move test for diagonal() to nat.nblast
  remove internal diagonal function
  refactor fc_subscoremat to use nat.nblast::sub_score_mat
  Switch default scoremats to explicitly check option
* closes #21
dev: git ignore figure directory

* i.e. the one produced by vignettes
Bump version to 0.5.1
git ignore a few more knitr products
ignore vignettes subdirs in build
rstudio: use devtools+roxygen
db can be a character argument

* also minor doc tweaks
fix missing symbols if plot3dfc called in function

* plot3dfc now uses plot3d.character/plot3d.neuronlist and this causes trouble when symbols in
  expressions are substituted. The safest thing to do seems to be to force evaluation,
  here by using do.call.
* was a bit worried that wrapping the db argument (which can be a huge neuronlist) could
  result in performance issues, but this appears not to be an issue since it is
  not actually modified.
* I tried to use substitute specifying an environment, but I wanted both the scope of the
  current function and the parent environment.
Bump version to 0.5.2
give hclustfc unsquare argument

* and give some more examples
test unsquare option
Merge branch 'feature/hclustfc-unsquare'

* feature/hclustfc-unsquare:
  test unsquare option
  give hclustfc unsquare argument
* closes #23
Add fc_sex utility function

* identifies sex for ids via fc_neuron
Bump version to 0.5.3