Merge pull request #194 from pwaller/doc-fixes

Fix documentation warnings for moved/renamed/deleted modules (#142)
Merge pull request #196 from pwaller/whatsnew

Add 'what's new' file
more incremental fixes for #142
Merge pull request #197 from ndawe/master

more incremental fixes for #142
create root_open and deprecate open
Merge pull request #198 from ndawe/master

create root_open and deprecate open
minor improvements to WHATSNEW.md
Merge pull request #199 from ndawe/master

minor improvements to WHATSNEW.md
improvements to RequireFile: also check that file is writable. New decorator module in extern to preserve docs and signature
check if curr_dir is ROOT.TROOT
put decorators in rootpy.decorators
file_check -> method_file_check file_cd -> method_file_cd and add file_check for any callable
decorators: comments and minor fix
add unit tests for decorators
YAGNI: remove file_check decorator
Merge pull request #200 from ndawe/master

MRG: refactor RequireFile code and add rootpy.decorators
remove deprecated use of rootpy.io.open
Merge pull request #204 from ndawe/master

remove deprecated use of root.io.open
add ignore_duplicates option for Tree.set_buffer
Merge pull request #205 from ndawe/master

add ignore_duplicates option for Tree.set_buffer