Initial go port of epics

internal/datasource/epics/epics.go

@@ -85,7 +85,9 @@ type EPICS struct {
 // caAddrList is used to set EPICS_CA_ADDR_LIST at runtime (may be empty to
 // rely on the environment).  archiveURL is the base URL of an EPICS Archive
 // Appliance instance for history queries (may be empty).
-func New(caAddrList, archiveURL string) datasource.DataSource {
+// pvNames is accepted for API compatibility with the pure-Go build but ignored
+// in the CGo build (the CGo implementation populates ListSignals via callbacks).
+func New(caAddrList, archiveURL string, pvNames []string) datasource.DataSource {
 	return &EPICS{
 		caAddrList: caAddrList,
 		archiveURL: archiveURL,