OS dependent features and general utilities in PHCv2.4.85

New in the second release is the inclusion of test programs (prefix "ts_").
A timer interfacing with C was needed for the Windows platform and Itanium
machines, moved in release 2.3 to a separate subdirectory Basic_Timer.
The unix timing facilities were moved to the subdirectory Unix_Timer.
An extra procedure was added to communications_with_user in release 2.3.
Multithreading was added in release 2.3.39.  New in 2.3.58 is the package
string_splitters.

Run "gprbuild system.gpr" to make all test procedures.
On windows, type "gprbuild system.gpr -Xos=windows"
at the PowerShell prompt.
The "gprclean system.gpr" removes all files created by gprbuild.

------------------------------------------------------------------------------
file name                 : short description
------------------------------------------------------------------------------
natural_io                : instantiation of text_io with natural
integer_io                : instantiation of text_io with integer
long_integer_io           : instantiation of text_io with long_integer
duration_io               : instantiation of text_io with duration
------------------------------------------------------------------------------
time_stamps               : date, time, and elapsed time
system_call               : allows to execute UNIX system commands
machines                  : specific system calls
unix_command_line         : handling arguments on the command line
bye_bye_message           : message at the end of the program
string_splitters          : reading and splitting a string along semicolon
communications_with_user  : dialogue to manipulate files, choose options
file_scanning             : scanning a file for text banners
string_parsing            : scanning a string for a banner
multithreading            : encapsulation for GNAT.Threads
------------------------------------------------------------------------------
ts_stamps                 : test on date, time, and elapsed time
ts_syscall                : execution of a system call : "ls"
ts_mach                   : prints system information of current process
ts_cmdline                : prints the arguments of the command line
ts_byemess                : prints the message at the end of the program
ts_strsplit               : tests string_splitters package
ts_commuser               : tests the dialogues with the user
ts_filescan               : reads a file name and banner, and scans for it
ts_striscan               : interactive test on string_parsing.scan()
ts_threads                : basic test on using GNAT interface to threads
------------------------------------------------------------------------------

A package like Unix_Command_Line is available in some form in most Ada
compiling systems.  For encapsulation purposes it is included here.

The file scanning operations are part of the database management of the
system input files to PHCpack.
