bug 335 - making sure it's possible to install from .apm files again. The UI needs improvement. Robustness could also be improved. May need to handle the case when there is a later version of a package in the packages directory than in the apm_workspace dir
making proc apm_bootstrap_load_libraries duplicate less of the logic in apm_load_libraries by making use of apm_get_package_files. To make this refactoring I had to move apm_backup_file_p, apm_include_file_p, and apm_ignore_file_p to 30-apm-load-procs.tcl