Virus Health Check checkhetdex

#checkhetdex - Check hetdex dither images

##Purpose:

Check the given images if they conform to the HETDEX standards for a HETDEX dither observations.

##Options:

`-N, --npixels <bool> [FALSE] Check for the correct number of pixels in the file.`
See VirusHealth::validate_size() for more details.

`-K, --keywords <bool> [FALSE] Check that the header keywords are correct.`
See VirusHealth::validate_keywords() for more details.

`-O, --overscan <bool> [FALSE] Check the rms of the overscan.`
See VirusHealth::validate_overscan() for more details.

`--ovc_mean <FLOAT> [1.0] Expected mean of the overscan.`

`--ovc_stddev <FLOAT> [0.2] Expected standard deviation of the overscan.`

`--max_ovc_dev_mean <FLOAT> [0.1] Maximum relative deviation for mean of overscan.`

`--max_ovc_dev_rms <FLOAT> [0.1] Maximum relative deviation for standard deviation of overscan.`

`-E, --exptime <bool> [FALSE] Check that the exposure time is at least 6 minutes long.`
See VirusHealth::validate_exptime() for more details.

`-S, --sky <bool> [FALSE] Check that the sky level in the fibers is above the required minimum.`
See VirusHealth::validate_sky() for more details.

`-s, --sky_level <float> [100.0] Required minimum sky flux.`

##Example:

Run all tests on a file:

> checkhetdex -N -K -O -E -S 20120908T192750_001LL_sci.fits