Fixed clang warnings about missing initializers for icalfileset_options structs.
Fixed an unused variable warning. die_on_errors_set isn't ever called, so we could just completely remove this function and the associated die_on_errors static variable.
Cleaned up unused variable and sign comparison warnings in icalarray.c.
Added explicit casts to silence sign-compare warnings.
Removed unused variables from icaltzutil_fetch_timezone.
Removed the unused calculate_pos function.
Changed import of icalerror.h and icaltz-util.h to look for icalerror.h locally.
Explicitly cast strlen to an int.
cast to ssize_t instead of int.
Initialize num_types to 0 to silence a clang warning.
Removed some invisible trailing whitespace.
Merge pull request #167 from ksuther/warning-fixes

Warning fixes
icalcomponent.c - remove execute bit