This roughly comprises the following changes:
- index target pools by job instead of scrape interval
- make targets within a pool exchangable while preserving existing
health state for targets
- allow exchanging targets via HTTP API (PUT)
- show target lists in /status (experimental, for own debug use)
``Target`` will be refactored down the road to support various
nuanced endpoint types. Thusly incorporating the scheduling
behavior within it will be problematic. To that end, the scheduling
behavior has been moved into a separate assistance type to improve
conciseness and testability.
``make format`` was also run.
This fixes a bug that has been annoying me minorly for some time now:
sometimes, after parse errors, a subsequent parser run would fail. The reason
is that yylex() modifies some global variables (yytext, yydata) during its run
to keep state. To make subsequent parser runs correct, these have to be reset
before each run.
Also, close files after reading them.
