Try to fix format-related compiler warnings for all systems

1. Address some compiler warnings (uninitialized vars).
2. Provide workaround for GCC compiler bug that remains outstanding for 3 years now.

Address compiler warnings on uninitialized variables

Address compiler warning

Address compiler warning

Address compiler warning

INTEGER to 64-bit native integer methods

aper: INTEGER longs to intmaxs

Copy operation

Class default syntax support

Update main README with supported encoding rules

jer: Remove implicit variables in ASN_DEBUGs

This reverts commit 818b21ba.

`NativeInteger_rfill.c` was sometimes ignoring the PER constrains. @lbm98 added a check which was also present in BIT_STRING_rfill.c to respect them.

.gitignore: Ignore generated smoke tests