Update main.cpp

[javl]

• More verbose output (whole sentences, capitals, etc.)
• Added --force argument (was already in code, but not accepted as argument)
• Added --available-platforms argument that returns a (hard-coded) list of available build platforms)
• Updated examples
• Don't throw error when called with only --help argument

[javl]

The Travis CI build failed, caused by some SSL error, which doesn't seem to be related to my pull request. Is it possible to somehow restart the check? Also: bump

[arturoc]

can you pull from master and push again? there was a problem with the travis builds but it should be fixed now