- support for package export and instal
   - opencensus_lib() now has a HDRS section just like Bazel.
   - opencensus_lib() allows declaration of headers in subdirectories, and installs them in proper directory
   - still issues with segregating public and private headers ( HDRS of non PUBLIC opencenus_lib )
     ( it looks like customer can write code that includes internal files )
   - still issues linking private static libraries together into bigger public ones. ( as Bazel does )

- attempt at allowing build as shared libraries
  - added helper code to request no undefined symbols in shared libraries.
  - attempt failed due to circular dependencies ( opencensus_trace and opencensus_context  ). Until those are fixed, only static libs will work.
  - outlined many missing dependencies declarations, only fixed in CMake for now.
    ideally similar changes would be done to Bazel build, and Bazel would allow to build shared libs as well...
  - stackdriver / googleapis / google-cloud-cpp changed recently, does not export monitoring/logging and cloud trace/tracing libs.

- attempt at building with FetchContent if and only if no existing package has been found.
  same ideas as using shared libraries :
  - reuse and to link ability into programs that may already use some of the same deps.
  - third party ( opencensus-cpp ) should not require significant alterations in consuming client build system ( hence CMake ) and strategy (

- linux-specifc example : using stackdriver exporter on Google Cloud Engine
  - parse /proc/meminfo and /proc/vmstat to stackdriver
  - rely via FetchContent on third party software
    - cpr ( to implement succintly access go GCE instance metadata server  )
    - re2 ( to brace against variable level of support/correctness in implementation of <regex> with old GCC versions )

- not yet verified on anything but CentOS 7
   - in particular no effort has been yet made so that CI via travis or appveyor actually works.
     As such, not ready to merge

…ocessor flag

…nstalling

…package() on gRPC and googleapis. No FetchContent yet

…TACKDRIVER_EXPORTER CMake option

… change, fix newest example

… it to pass its own unit tests when used with FetchContent ...

…mat and cmake-format manually as docker-format Dockerfile is obsolete. format check should match travis one

…ast file to add