* remove injection hook for textfile metrics, convert them to prometheus format
* add support for summaries
* add support for histograms
* add logic for handling inconsistent labels within a metric family for counter, gauge, untyped
* change logic for parsing the metrics textfile
* fix logic to adding missing labels
* Export time and error metrics for textfiles
* Add tests for new textfile collector, fix found bugs
* refactor Update() to split into smaller functions
* remove parseTextFiles(), fix import issue
* add mtime metric directly to channel, fix handling of mtime during testing
* rename variables related to labels
* refactor: add default case, remove if guard for metrics, remove extra loop and slice
* refactor: remove extra loop iterating over metric families
* test: add test case for different metric type, fix found bug
* test: add test for metrics with inconsistent labels
* test: add test for histogram
* test: add test for histogram with extra dimension
* test: add test for summary
* test: add test for summary with extra dimension
* remove unnecessary creation of protobuf
* nit: remove extra blank line
* Move NodeCollector into package collector
* Refactor collector enabling
* Update README with new collector enabled flags
* Fix out-of-date inline flag reference syntax
* Use new flags in end-to-end tests
* Add flag to disable all default collectors
* Track if a flag has been set explicitly
* Add --collectors.disable-defaults to README
* Revert disable-defaults flag
* Shorten flags
* Fixup timex collector registration
* Fix end-to-end tests
* Change procfs and sysfs path flags
* Fix review comments
Named return variables should only be used to describe the returned type
further, e.g. `err error` doesn't add any new information and is just
stutter.
This puts all collector-specific flags into their own namespace under
"collector.<collector-name>", and moves from camel case to dashes, which
is the standard in Prometheus land now.
This allows static metrics (e.g. an attributes collector replacement),
and cronjobs to expose stats by echoing into a file.
For example:
echo "my_metric 123" > mycronjob.prom.$$
mv mycronjob.prom.$$ mycronjob.prom
