* bump vendor/nimbus-build-system
- add the Nim compiler header to the Nimbus header
- also support the USE_LIBBACKTRACE env var
* "go-checks" target no longer available
- moved "nimbus/api" to "wrappers"
- renamed files
- replaced the build scripts with Makefile targets
- set the rpath relative to the test binary's location so it can look
for libnimbus.so there at runtime
- libnimbus.so.0 required on Linux, apparently
- compiled all the Nimbus code with `--app:lib`, not just one file (this
required skipping a proc in "nimbus/config.nim" because it uses an API
that's unavailable in libraries)
- removed static linking from the Go wrapper. It doesn't make sense at a
global level, when using a shared Nimbus library. To selectively link
static libraries, we should probably be specifying them as *.a. I did
build a static libnimbus.a, as a test, but it insisted on dlopen-ing a
shared version of itself which looked too ugly to continue.
- dynamically generated copyright year interval
- added the db backend to the header
- documented the db-backend-changing define, made it case insensitive
and ensured wrong values would trigger compilation errors
- skipped the tests in allowedFailInCurrentBuild()
- replaced doAssert() with check() in testFixtureIndexes() so we can see
both hash values on failure
- checking filename extension for JSON tests to avoid editor swap files
- replaced the duplicated block values in the main net's ChainConfig
with values from forkBlocks
- allowed overriding the current fork in computations, because the old
strategy of only looking at the block number doesn't work with JSON tests
where the block number is usually 1
- explicitly pass the fork to gasCosts() and use it for conditional cost
calculation
- fixed a logic error in the CREATE opcode
- fixed VM selection based on current fork in updateOpcodeExec()
- single point of control for supported forks in tests (just one fork, at the
moment)
- 44 new test failures (that were probably passing for the wrong reasons)
