h4h5tools

Purpose:
bug fix
Description:
1. In H4toH5_all_dimscale, h5dsetname may be NULL, and this will cause some h4toh5 crashed.
2. HDF4 object name can be something like Land/Mask, this relative name is invalid in HDF5. In previous
H4toH5 utility, Land/Mask will be replaced as Land_Mask.
In H4toH5 library, for some cases, the object name is forgotten to check.
Solution:
correct 1,2
Platforms tested:
w2000,linux2.2.18smp