SPLICE for "gene" splicing, cutting, copying, inserting and
        overlaying bits of a file into another.
Uses for SPLICE:
1. excising a section of a file.
2. replacing a section of a file.
3. inserting a section into a file.
4. extracting a section of a file.
5. appending a section onto a file.
Splice is designed to work on text files. For audio files,
you would use an audio editor like GoldWave. For word
processing files, you would use the word processor that
created the two files. It can be used on binary files in the
rare instance just butting the files together is sufficient.
SPLICE commands, may be upper or lower case:
SPLICE CUT MyFile1.Txt START 6 LENGTH 5 RECSIZE 1024
    remove a slice from a file offset 6 length 5
    Offsets and lengths are measured in blocks of 1024.
SPLICE CUT MyFile1.Txt START 6 LENGTH 5 TO MyFile2.txt RECSIZE 1024
    remove a slice from a file offset 6 length 5
    and copy it to a new file.
SPLICE CUT MyFile1.Txt START 6 LENGTH 5 APPEND MyFile2.txt RECSIZE 1024
    remove a slice from a file offset 6 length 5
    and copy it to the end of another file.
SPLICE CUT MyFile1.Txt START 6 LENGTH 5 OVERLAY MyFile2.txt AT 7 RECSIZE 1024
    remove a slice from a file, offset 6 length 5,
    overlay it on top of another file at offset 7.
SPLICE CUT MyFile1.Txt START 6 LENGTH 5 INSERT MyFile2.txt AT 7 RECSIZE 1024
    remove a slice from a file, offset 6, length 5, insert
    at offset 7 in another file
SPLICE COPY MyFile1.Txt START 6 LENGTH 5 TO MyFile2.txt RECSIZE 1024
    copy a slice from a file offset 6 length 5
    to a new file
SPLICE COPY MyFile1.Txt START 6 LENGTH 5 APPEND MyFile2.txt RECSIZE 1024
    copy a slice from a file offset 6 length 5
    to the end of another file.
SPLICE COPY MyFile1.Txt START 6 LENGTH 5 OVERLAY MyFile2.txt AT 7 RECSIZE 1024
    copy a slice from a file, offset 6 length 5,
    overlaying it on top of another file at offset 7,
    replacing the previous data.
SPLICE COPY MyFile1.Txt START 6 LENGTH 5 INSERT MyFile2.txt AT 7 RECSIZE 1024
    copy a slice from a file, offset 6, length 5, inserting
    at offset 7 in another file.
START defaults to 0
AT defaults to 0
RECSIZE defaults to 1
If length reaches out past the end of the source file, it will be shortened.
Target files will be expanded as needed with zeroes.
Because of the antiquity of this program it uses 32-bit rather than 64-bit
arithmetic internally.  This limits it to files of 2 GB.  It is on my todo
list to extend it.
This program may be freely copied and used for any purpose except
military.  C++ source included.