h4h5tools

This and the next check-in partially address the JIRA ticket https://jira.hdfgroup.uiuc.edu/browse/HFRHFVTOOLS-50 Upgrade to use V18 API.
Only the default configuration option is addressed. After this check-in, the configuration with -eos option will also be double checked and potentially some APIs may also need to upgrade to V 18. Then the installation and the release notes will also be updated. 

Macros are defined as follows to make the toolkit work with the 1.8 and the 1.6 without using defining CPPFLAGS=-DH5_USE_16_API.
Note: The parameters in H5Aoperator2_t operator in H5Aiterate2(version 18) is different than the parameters in H5Aoperator1_t in H5Aiterate1(version 16). The call back function(convert_attr) inside h5toh4.c cannot simply cast to H5Aoperator2_t. More work need to be
done with the convert_attr() to make it work with H5Aiterate2, which is not part of the exercise of this ticket. So H5Aiterate1 is still used for this release. Tested with 1.6.10 and 1.8.7 on jam.



if H5_VERS_MAJOR == 1 && H5_VERS_MINOR == 6

define H5DCREATE(fd, name, type, space, dcpl) H5Dcreate(fd, name, type, space, dcpl)
define H5DOPEN(fd, name) H5Dopen(fd, name)
#else
define H5DCREATE(fd, name, type, space, dcpl) H5Dcreate2(fd, name, type, space, H5P_DEFAULT, dcpl, H5P_DEFAULT)
define H5DOPEN(fd, name) H5Dopen2(fd, name, H5P_DEFAULT)
#endif