Log Message:
Update to 2.5.6

Upstream changes:
v2.5.6 2018-08-13T22:47:57Z
    - Revert "Warn if accessors overwrite methods/functions" for now; \ 
it may cause crashes in perl 5.28.0 (#94)

v2.5.5 2018-08-13T15:41:32Z
    - Warn if accessors overwrite methods/functions (ybrliiu #86, #90, #93)
    - Fix for threads and XS; use newSVpvs instead of newSVpvs_share \ 
(sergeykolychev #92)