DLCORE is a program and a library.  Together they provide a mechanism
for building programs that dynamically load/link code to extend their
functionality.  The collection of procedures and symbols that get
loaded and link are called a package.  Each package is described by a
text file which contains commands to the DLCORE load/link engine.
These commands allow the user to completely specify how to add a
package to a running process.  The process may use the DLCORE library
procedures to inspect and manipulate packages and their procedures and
symbols.  The DLCORE API and the load/link engine scripting language
are purposely designed to be very simple and provide only lowlevel
functions.

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Need structure that represents the symbols contained in a .o or .a
file.  Need to link that to a structure that represents a package.

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Basic functionality:

run package file through preprocessor
add a package
remove a package
determine unresolved symbols
link a .o file
link against a .a file
use a search path to locate files (.o and .a) to load/link
allow user to modify load/link search path

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The DLCORE program maintains an external pointer to a procedure called
dlcore_main which should exist after all of the user's intitial
package has been added.  The procedure may be defined as one of the
symbols in the user's package or one of the packages that it relies
upon.  After the initial package is sucessfully added the dlcore_main
procedure will be called to hand control over to the user's
application.  Additionally each package may define procedures to be
executed after being sucessfully added, after failing to be added and/or
before being removed.  The DLCORE engine will execute these procedures
at the predetermined time.

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The scripting language used to describe packages is very simple:

package_name name

link filename

call funcname arg

     arg is either a sting literal, a character literal, an integer, a
     double or a special value represented by an escape sequence.
     Escape sequences include: %pkg - string name of package, %pkgfile
     - string name of package file, %addr sym - the resolved address
     of the symbol, %linkname - filename given to lask link command