* refactor: Centralize MIB include directory specification
The default is now:
```
$config['mib_dir'].'/mibdirname:'.$config['mib_dir']
```
This means we exclude OS mibs and only use ours (we could prepend `+` if we want to include os mibs.
All snmp calls should only include the name of the subdirectory under the mibs directory.
* Remove d_echo from Proc
Fix snmpsim tests.
fallback feature so we don't have to run snmpsim on devel computers, should be adequate for now
./scripts/pre-commit.php -u -snmpsim will start an snmpsimd.py process automatically
* refactor: OS Discovery cleanup (Part 1)
Convert linux.inc.php to use new string functions
Create OS discovery tests
Use glob instead of readdir in os discovery (could change discovery order)
Stop discovering once $os is set
* Remove duplicate file header.
