Target for copying files and directories

It is sometimes useful to copy files form one place to another during the compilation stage. For instance, this makes it possible to create a python package inside the build directory and use it during testing. The process is to create a dummy target and add files to it:

include(TargetCopyFiles)
add_custom_target(mynewtarget ALL)
add_copy_files(mynewtarget thisfile DESTINATION this/directory)
add_copy_directory(mynewtarget path/to/this/directory
   RELATIVE path/to
   DESTINATION copy/to/here
   GLOB *.h
   EXCLUDE *.c
)

A few options are available, as described below:

add_copy_files(
   <target>                          ## target name
   [DESTINATION <destination>]       #  directory where files will be copied
                                     #   Defaults to current binary directory
   [GLOB <glob>]                     ## a glob to find target files to copy
   [REPLACE <pattern> <replacement>] ## string(REGEX REPLACE) arguments on output filename
   [FILES <list of files>]           ## list of files to copy. Cannot be used with GLOB or ARGN.
   [<list of files>]                 ## list of files to copy. Cannot be used with GLOB or FILES.
)

add_copy_directory(<target>      ## target name
   <path>                        ## directory to copy stuff from
   [DESTINATION  <path>]         ## directory where stuff is copied
                                 #  Defaults to current binary dir
   [RELATIVE <path>]             ## files placed in <destination> from <directory> 
                                 #  will be named relative to this directory. 
                                 #  Defaults to <directory>.
                                 #  In the example above, "copy/to/here" will contain 
                                 #  files such as "this/directory/somefile" 
   [GLOB <glob0> <glob1> ...]    ## Patterns copied files should match. Defaults to "*".
   [EXCLUDE <glob0> <glob1> ...] ## Patterns of files that should not be copied
)