Log Message:
Changes 2.1.5:
- added protection code against bad_alloc exception
- new configure option to bypass libdl test
- removed expected exception list in deci, limitint, real_infinint
  and storage modules to improve global robustness
- remove the #pragma implementation/interface directives
  which tend today to become obsolete, and seems to be the
  cause of compilation problem on (recent) Linux kernel 2.6.7
  for example.
- added protection code to report bug conditions
- code simplification for filesystem reading (while performing
  backup)
- fixed bug #29 (crash when saving hard link without read
  permission)
- fixed code syntax to support gcc-3.4.x