Automatic generation of version header

[michaeltryby]

This PR configures cmake to automatically generate a version.h file for SWMM including

• version info (as string and as integer) from cmake project definition
• long git hash (as string) for commit currently being built
• a UTC datetime stamp (as string) to uniquely identify the build

The build option GEN_VER_HEADER has been defined to control version header generation. For example, during development the version header "rolls" with the most current information. During release, however, we will freeze the information in the version header.

See discussion in Issue #352

[michaeltryby]

@cbuahin Couple of things are accomplished in this PR:

• swmm version now equals cmake project version. Only need to update version in one place.
  • git hash allows us to precisely identify the exact version of the code
  • build identifier allows us to precisely identify the build that created a binary
  • OWA SWMM fully adopts semantic versioning. Let’s drop legacy versioning format
  • A formatted version string is provided this simplifies getter code
  • Major, minor, and patch versions are available as integers. For easy version number comparison

[jennwuu]

Will this PR include changes to SWMM report file to include build source?

[michaeltryby]

@jennwuu as per your request I performed the updates discussed in Issue #352.

[jennwuu]

@michaeltryby Why is window build failing?

[michaeltryby]

Fixed an MSVC syntax error. Switched over to a cmake generated export header so we can export functions with pointers as return values. This greatly simplifies working with VERSION and BUILD_ID strings.

[michaeltryby]

This PR is ready for review.

[jennwuu]

Hi @michaeltryby just to double check, we are aware that ubuntu build is not working atm right? I recall a conversation related to that in another PR.

[michaeltryby]

Yes I recommend we fix that in another PR.

[michaeltryby]

@jennwuu I built the PR using WSL Ubuntu. Everything checks out.

[michaeltryby]

Oops!