Add "const" to function prototypes where appropriate

[skliper]

In particular, this should be done at least for functions that accept char * strings but do not modify them. If a string literal (by definition a const char *) is passed into function argument that is declared a non-const char *, a compiler warning may be generated and the build will fail if compiled with strict settings.

This ticket will add "const" to function parameters where appropriate.

[skliper]

Imported from trac issue 9. Created by jphickey on 2014-12-30T20:44:18, last modified: 2019-03-05T14:57:55

[skliper]

Trac comment by jphickey on 2015-01-26 13:18:17:

Merged into ticket #59

[skliper]

Trac comment by jhageman on 2019-03-05 14:57:55:

Milestone renamed