Merge branch 'fix-db-load-cell' into 'master'

Split db load and create cell to avoid forced recreates

See merge request rc-data-science/createandparsesacct!7

slurm-2sql.ipynb

 %% Cell type:code id: tags:
 
 ``` 
 import sqlite3
 import slurm2sql
 import pandas as pd
 ```
 
 %% Cell type:code id: tags:
 
 ``` 
 db = sqlite3.connect('test.db')
+```
+
+%% Cell type:code id: tags:
+
+``` 
 slurm2sql.slurm2sql(db, ['-S', '2020-03-18', '-a'])
 ```
 
 %% Cell type:code id: tags:
 
 ``` 
 # For example, you can then convert to a dataframe:
 df1 = pd.read_sql('SELECT * FROM slurm', db)
 ```
 
 %% Cell type:code id: tags:
 
 ``` 
 df1.head(5)
 ```
 
 %% Cell type:code id: tags:
 
 ``` 
 print("more plots to come")
 ```
 
 %% Cell type:code id: tags:
 
 ``` 
 ```