Fix for vector memory allocation error

The new anonymised ccRecords were causing R to crash when using create_cctable(). This is because the findMaxTime function was returning the number of hours since 1970 and forcing vector allocation to this amount. This fixes the issue

.Rbuildignore

@@ -3,3 +3,5 @@ Makefile
 .travis.yml
 appveyor.yml
 paper.md
+^.*\.Rproj$
+^\.Rproj\.user$

.gitignore

@@ -24,3 +24,4 @@ vignettes/*.pdf
 
 # OAuth2 token, see https://github.com/hadley/httr/releases/tag/v0.3
 *.httr-oauth
+.Rproj.user

R/ccTable.R

@@ -452,9 +452,13 @@ getEpisodePeriod <- function (e, unit="hours") {
     # The failure of POSIX conversion indicates that this episode is either 
     # anonymised or has a missing or incorrect value of discharge or admission
     # time. 
-    if (is.na(tadm) || is.na(tdisc))
-        period_length <- findMaxTime(e)
-    else {
+    if (is.na(tdisc)) {
+        period_length <- ceiling(
+          as.numeric(
+            difftime(
+              as.POSIXct.numeric(findMaxTime(e), origin = "1970-01-01 00:00:00"), tadm, units = unit)
+          ))
+    } else {
         if (any(is.null(tdisc), is.null(tadm)))
             period_length <- NULL
         else
@@ -466,6 +470,8 @@ getEpisodePeriod <- function (e, unit="hours") {
         if (period_length == 0)
             period_length <- period_length + 1
     }
+
+
 
     if (is.null(period_length))
         warning("This episode does not have any time series data: ",