Better tag parsing for things like erroneous spaces

[flowchartsman]

An accidental space can currently break tag parsing in unfortunate ways. The most insidious example being:

type ServiceConfig struct {
        InfluxAddr     string `conf:"help:address to influxdb"`
        InfluxDB       string `conf:"help:influx database to use"`
        InfluxUserName string `conf:"help:influxdb username"`
        InfluxPassword string `conf:"help:influxdb password, noprint"`
 }

Where the config parses just fine, but the space before noprint causes it to be omitted, meaning INFLUX_PASSWORD will appear in the result of conf.String() No bueno.

[flowchartsman]

strings.TrimSpace() Maybe. At the very least should have default clauses in parseTags()

[flowchartsman]

Also needed:

• strings with commas
• default values for lists