string functions plugin
This plugin provides some basic string functions. This plugin will always be linked statically into LCD4Linux, and therefore does not follow the 'plugin_name::function' scheme.
Functions:
| strlen(s) | length of the string |
| strupper(s) | upper case version of s |
| strstr(haystack, needle) | position of substring needle in haystack or -1 if not found |
| substr(string, pos) | substring starting at pos |
| substr(string, pos, len) | substring starting at pos, up to len characters |