Following command fails under visual studio.
    ncdump -h http://thredds.ucar.edu/thredds/dodsC/nexrad/composite/gini/n0r/1km/20170216/Level3_Composite_n0r_1km_20170216_1635.gini

The problem is that sscanf for windows does not appear to support
scanning 8bit integers: it appears to only allow scanning of characters.

Solution:
Scan the input as an integer (for type Byte) or unsigned int (for type UByte)
and then recast the result as a char or unsigned char.

Primary code fix is in libdap2/dapcvt.c#dapcvtattrval

re: #365

1. Added to RELEASENOTES.md
2. Add a range check to more closely
   mimic unix sscanf
3. locate and fix same sscanf problems in ncgen/cvt.c

Still need a stable url for a test case.

2. invoked makeparser using bison 3.0.4 and flex 2.5.35