* Prefer python3 over python(2) in checkout-deps
We require Python 3 and don't want to accidentally use Python 2 if both are available.
* Use python3 in travis build
* Install python3-pip package on travis trusty image
* Fix pip detection in checkout-deps.sh
This is a pretty big diff because SourceMod had lots of multi-arch
workarounds that can now go away. I've also changed 'x64' to 'x86_64' in
many places since this is how AMBuild normalizes it, and it's far too
late to pick the shorter string, so we might as well suck it up.
The --target-archs parameter has been replaced with --targets. It works
the same way.
The default behavior for SDK inclusion is now "present" instead of
"all" since this lowers the burden of storing many SDKs. Official builds
will still be made with --sdks=all.
SourceMod doesn't support Source 1 Dota 2 anymore and neither Source 2. Speed up CI by only cloning the hl2sdks that are tested.
This adds a `-s sdk1,sdk2` parameter to the checkout-deps.sh script similar to the `-SDKs` option of the powershell script to select specific sdks to update instead of all.
Our official builds use clang-3.4 (for macOS) and clang-3.8 for Linux.
Linux uses libstdc++-4.9. Make sure these two compilers are being tested
and that libstdc++-4.9 is being used for STL.
Add a macOS builder to get coverage there. This will use a newer
clang than we actually use, but as opposed to the linux builder will
test the platform-specific bits.
Finally, use the latest GCC and clang versions from a bionic image, so
we have some coverage of a popular distribution.
