OSL 1.10.5

Release 1.10.5 -- May 1, 2019 (compared to 1.10.4)

• Extend linearstep() and smooth_linearstep() to work with color, point,
  vector, and normal types (previously restricted to float). #994
• Improve oslc type error detection for variable declarations with init
  expressions. Note that this may flag some warnings and errors that went
  undetected before, involving initialization assignments of incompatible
  types. #991, #993
• Add a build-time option GLIBCXX_USE_CXX11_ABI to force the "new/old string
  ABI" to something other than the default for your version of gcc. #995