move exception functions to exception.d
Merge pull request #564 from WalterBright/move-to-exception

move exception functions to exception.d
fix Issue 10711 - shared phobos library should not depend on _Dmain
Merge pull request #563 from WalterBright/fix10711

fix Issue 10711 - shared phobos library should not depend on _Dmain
Split exception handling in deh/deh_win32/deh_win64_posix

The original file names (deh and deh2) are not very descriptive. This
structure is inspired by the section and section_xxx modules.

_d_createTrace() implementation is left in the deh module because is
common to all the architectures.
Merge pull request #565 from leandro-lucarella-sociomantic/deh-split

Split exception handling in deh/deh_win32/deh_win64_posix