Merge branch 'release/v0.3.0' into develop
Preparation for the first stable/production release
Fixed auto-installer for Windows OS (bug with %PATH% customisations)
Updated "prog_name" to PlatformIO
Added alternative "Quick-Install" version with only one command  for Mac/Linux user
Retested with click 2.3
Added "Embedded Platform Boards" section with pre-configured settings for most popular boards
Retested with Click 2.4
Implemented "$ platformio serialports" command
Allowed special build flags only for "src" files via "SRCBUILD_FLAGS" or global environment "export $PIOSRCBUILD_FLAGS"
Allowed to change default ".pioenvs" directory with global env "export $PIOENVS_DIR"
Added support to override UPLOAD_PORT via cli-option "$ platformio run --upload-port="
Implemented especially for SmartAnthill "$ platformio run -t uploadlazy" target (no dependencies to framework libs, ELF and etc.)
PyLint fix for CI
Filled README & HISTORY with latest additions
Added simple menu with navigation by README
Corrected README menu
Fixed GitHub issue with RST bold
Added "Examples" to README menu
Added "Blog" to README menu