v0.2.0: Felix 0.2.0: Separate Standard_Text from C_Standard_IO

Other new features include:
- The C_Standard_IO and Native_Language_System packages have been
  rewritten to comply with the 1987 version of the ISO Ada standard.

* alire.toml: Add a dependency on catgets for Windows, as the
necessary nl_types.h C header is not supplied by default.
* examples/example1.adb:
- Add MIT-0 license.
- Add usage instructions.
- Adapt to API changes
- Minor formatting changes.
* felix.gpr:
- Increment library version: 0.1.0 -> 0.2.0.
- Rename System to System_API.
- Silence warnings (J) about the use of Ada 1987 pragmas like
  Interface.
- Drop front-end inlining, which was inadvertently copied from
  BLAKE2S.
* src/cstandio.ads
* src/cstandio.adb:
- Rewrite for Ada 1987 compatibility.
- Remove the printf() emulation functions to Standard_Text.
- Wrap the C fprintf* and sprintf* functions within Ada functions for
  the use of Standard_Text.
- Change the Null_Output function to the procedure Open_Null, as null
  files must be closed like any other.
- Make Standard_Output the default File for output routines.
- Add new *_Image functions that use sprintf.
* src/nalansys.ads
* src/nalansys.adb:
- Rewrite for Ada 1987 compatibility. Unfortunately, this prohibits
  marking the imported C constants as constants or the fully defined
  types as limited.
- The Message function is now a more direct catgets() interface, and
  has no knowledge of Standard_Text's printf() emulation.
* src/posix/csionuou.adb
* src/win32/csionuou.adb: Rename for Null_Output to Open_Null change.
* src/stantext.ads
* src/stantext.adb:
- New location for Felix's printf() emulation. This change facilitates
  the future creation of an Enhanced_Text package utilizing Ada-native
  printing routines and keeps the Ada 1995 features separate from the
  interface packages.
- All imported/interfaced procedures and functions have been removed
  to C_Standard_IO or Native_Language_System, as appropriate.