File Import

- Added format identifier code for task 1.4.3, task 1.5.0, todo.sh
  2.0 and CSV.
- Implemented import for type text.
- Implemented util.cpp:slurp function.
- Gathered sample input files for import testing, and later, unit
  tests.

src/import/freeform.csv

@@ -0,0 +1,4 @@
+'id','priority','description'
+1,H,'this is a test'
+2,,'another task'
+

src/import/line.txt

@@ -0,0 +1,3 @@
+This is a test priority:H project:A
+Another task
+

src/import/task-1.4.3.csv

@@ -0,0 +1,2 @@
+'id','status','tags','entry','start','due','end','project','priority','fg','bg','description'
+'545629d2-24a3-4a32-8894-57e708b98354','pending','',1238037900,,,,'A','M',,,'foo bar '

src/import/task-1.5.0.csv

@@ -0,0 +1,2 @@
+'id','uuid','status','tags','entry','start','due','recur','end','project','priority','fg','bg','description'
+'7f7a4191-c2f2-487f-8855-7a1eb378c267','pending','',1238037947,,,,,'A','M',,,'foo bar'

src/import/todo.txt

@@ -0,0 +1,2 @@
+x 2009-03-25 Walk the dog +project @context
+This is a test +project @context