Tony's comment on output format
Update release instructions for new robots.txt file
Inline helper functions of label
Add option to return number of labels
Add test case for number of labels
fix to preserve input image shape upon executing `random_walker`
PEP8 fixes; remove unneeded pyamg import; add `data` shape check
Use `force_copy` argument of `img_as_float`

Also three PEP8 fixes
Remove duplicate import statement
fix: remove unnecessary forced copy
add assertion checks to ensure `data` shape is unchanged
Merge pull request #500 from JDWarner/fix_preserve_rw_input_shape

BUG: Preserve input image shape upon executing `random_walker`.
Merge pull request #503 from ahojnnes/exposure

STY: Remove duplicate import statement.
Merge pull request #494 from ahojnnes/release-instr

DOC: Update release instructions for new robots.txt file.
add option full_output to hough_circ
Fix 64-bit multipage tiff writing segfault
Merge pull request #507 from zachrahan/freeimage-multipage-64

Fix 64-bit multipage tiff writing segfault
Merge pull request #496 from ahojnnes/label-performance

ENH: Inline helper functions of label and add number of regions as an optional return.
Add multipage TIFF unittest
Merge pull request #508 from zachrahan/freeimage-multipage-64

Add multipage TIFF unittest