The vcc_feature parameter is in charge of translating param.set calls
from the alias name to the bit flag. On the other hand param.show will
defer to the generic alias display.

With this change we lose the "camel case" functions used to set those
bits through functions between mgt and libvcc. The functions were
renamed VCC_Opt_<lowercase> to look more appropriate than "all_lower"
or "ALL_UPPER".